As the author of 2Peter said
2Pet. 3:15 καὶ τὴν τοῦ κυρίου ἡμῶν μακροθυμίαν σωτηρίαν ἡγεῖσθε, καθὼς καὶ ὁ ἀγαπητὸς ἡμῶν ἀδελφὸς Παῦλος κατὰ τὴν δοθεῖσαν αὐτῷ σοφίαν ἔγραψεν ὑμῖν, 16 ὡς καὶ ἐν πάσαις ἐπιστολαῖς λαλῶν ἐν αὐταῖς περὶ τούτων, ἐν αἷς ἐστιν δυσνόητά τινα, ἃ οἱ ἀμαθεῖς καὶ ἀστήρικτοι στρεβλοῦσιν ὡς καὶ τὰς λοιπὰς γραφὰς πρὸς τὴν ἰδίαν αὐτῶν ἀπώλειαν.
2Cor. 2: 2 εἰ γὰρ ἐγὼ λυπῶ ὑμᾶς, καὶ τίς ὁ εὐφραίνων με εἰ μὴ ὁ λυπούμενος ἐξ ἐμοῦ;
Commentators ancient and modern have had difficulties
agreeing on what to make of 2Cor. 2:2. Chrysostom and others appear to read it as if Paul was in some sense pleased or gratified (?) that his former letter(s) had caused pain. Alford and Meyer think this reading doesn’t fit the immediate context.
2Cor. 1:23 Ἐγὼ δὲ μάρτυρα τὸν θεὸν ἐπικαλοῦμαι ἐπὶ τὴν ἐμὴν ψυχήν, ὅτι φειδόμενος ὑμῶν οὐκέτι ἦλθον εἰς Κόρινθον. 24 οὐχ ὅτι κυριεύομεν ὑμῶν τῆς πίστεως ἀλλὰ συνεργοί ἐσμεν τῆς χαρᾶς ὑμῶν· τῇ γὰρ πίστει ἑστήκατε. 2:1 Ἔκρινα γὰρ ἐμαυτῷ τοῦτο τὸ μὴ πάλιν ἐν λύπῃ πρὸς ὑμᾶς ἐλθεῖν. 2 εἰ γὰρ ἐγὼ λυπῶ ὑμᾶς, καὶ τίς ὁ εὐφραίνων με εἰ μὴ ὁ λυπούμενος ἐξ ἐμοῦ; 3 καὶ ἔγραψα τοῦτο αὐτό, ἵνα μὴ ἐλθὼν λύπην σχῶ ἀφ᾿ ὧν ἔδει με χαίρειν, πεποιθὼς ἐπὶ πάντας ὑμᾶς ὅτι ἡ ἐμὴ χαρὰ πάντων ὑμῶν ἐστιν.
Greek Testament Critical Exegetical Commentary - Alford
2.] γάρ, reason why I would not come to you in grief: because I should have to grieve those who formed my proper material for thankfulness and joy.
ἐγώ has a peculiar emphasis: ‘If I cause you grief’.… implying, ‘there are who cause you sufficient.’
καί prefixed to a question denotes inconsequence on, or inconsistency with, the foregoing supposition or affirmation: so Eur. Med. 1388, ὦ τέκνα φίλτατα! “μητρί γε, σοὶ δʼ οὔ.” κἄπειτʼ ἔκτας; see other examples in Hartung, Partikellehre, i. p. 147. It is best expressed in English by ‘then:’ who is he then, &c. as in E. V.
The explanation of Chrys., who has been followed by Erasm., Bengel, Olsh., al., is curious, and certainly inconsistent with the context: εἰ καὶ λυπῶ ὑμᾶς, χάριν μοι παρέχετε κἀν τούτῳ μεγίστην, ὅτι δάκνεσθε ὑπὸ τῶν παρʼ ἐμοῦ λεγομένων. Hom. iv. p. 456. Some of these Commentators refer the singular to the offender, vv. 5-8. But however the words may bear the meaning, and however true the saying might be, it is pretty clear that it would be beside the subject: nay, would give a reason the other way,—why he should come to them.
Alford's citation from Chrysostom:
Εἰ καὶ λυπῶ ὑμᾶς, χάριν μοι παρέχετε κἀν τούτῳ μεγίστην, ὅτι δάκνεσθε ὑπὸ τῶν παρ' ἐμοῦ λεγομένων.
for καὶ ἐν not
καὶ ἄν, καὶ ἐν τούτῳ is an adverbial "even in this." Hyperbaton χάριν ... μεγίστην.
"Though I make you sorry, even herein ye bestow on me a very great favor in that ye are hurt at what I say." Rev. J. Ashworth, C. M. Marriott, T. W. Chambers
Meyer's NT Commentary
2 Corinthians 2:2. As reason for his undertaking not to come to his readers again ἐν λύπῃ, Paul states that he on his own part could not in this case hope to find any joy among them. Comp. 2 Corinthians 2:3. For if I afflict you, who is there also to give me joy, except him who is afflicted by me?—i.e., if I on my part (ἐγώ is emphatic) make you afflicted, then results the contradiction that the very one who is afflicted by me is the one who should give me joy. Against this view Billroth and Rückert object that εἰ μὴ … ἐμοῦ is superfluous, and even in the way. No; it discloses the absurdity of the case conditioned by εἰ ἐγὼ λυπῶ ὑμᾶς. Pelagius, Bengel, and others, including Billroth, render: who yet so much gladdens me as he who lets himself be afflicted by me (which is a sign of amendment)? Comp. Chrysostom, and Theodoret, Erasmus, and others. So also Olshausen, who sees here an indirect warning to take the former censure more to heart. But against this perversion of ὁ λυπούμενος in a middle sense, we may decisively urge:—(1) that the sense of 2 Corinthians 2:2 would not stand in any relation to 2 Corinthians 2:1 as furnishing a reason for it; and (2) the οὐχ ἵνα λυπηθῆτε in 2 Corinthians 2:4. Rückert sees in εἰ … ὑμᾶς an aposiopesis; then begins a new question, which contains the reason why he may not afflict them, because it would be unloving, nay, ungrateful, to afflict those who cause him so much joy. Hence the meaning, touchingly expressed, is: “I might not come to you afflicting you; for if I had done so, I should have afflicted those very ones who give me joy: this would have been unloving on my part.” This is all the more arbitrary, since, logically at least, it must have stood in the converse order: καὶ τίς ἐστιν ὁ λυπούμενος ἐξ ἐμοῦ εἰ μὴ ὁ εὐφραίνων με. Hofmann holds still more arbitrarily and oddly that εἰ γάρ is elliptical protasis, and ἐγὼ λυπῶ ὑμᾶς apodosis: if I come to you again in affliction, I make you afflicted, and who is there then who gladdens me, except him whom affliction coming from me befalls? The well-known omission of the verb in the protasis after εἰ is, in fact, a usage of quite another nature (see Hartung, Partikell. II. p. 213; Stallbaum, ad Plat. Rep. p. 497; Krüger, § lxv. 5. 11). Besides, this subtlety falls with Hofmann’s view of 2 Corinthians 2:1.
καί] also, expresses after the conditional clause the simultaneousness of what is contained in the apodosis, consequently without the interrogative form: there is also no one, etc. See Hartung, Partikell. I. p. 130 f.; Buttmann, neut. Gramm. p. 311 [E. T. 362].
ὁ λυπούμενος] does not mean the incestuous person (so, against the entire connection, Beza, Calovius, Cornelius a Lapide, Heumann); but the singular of the participle with the article denotes the one who gives joy, as such, in abstracto. Comp. 1 Peter 3:13, al.; Xen. Cyr. ii. 2. 20, al. Paul might have written τίνες εἰσὶν οἱ κ.τ.λ., but he was not under necessity of doing s.
ἐξ ἐμοῦ] source of the λυπεῖσθαι. See Bernhardy, p. 227; Schoem. ad Is. p. 348; Winer, p. 345 [E. T. 385]. Comp. ἀφʼ ὧν, 2 Corinthians 2:3; but ἐξ is “quiddam penitius,” Bengel.
 This emphasis is usually not recognised. But in the ἐγώ there lies a contrast to others who do not stand in such an intimate relation to the readers as Paul. Comp. Osiander.
For the citation I have provided the context. The quote from Chrysostom as cited by Alford comes at the very end of his discussion 2Cor 2:2 shown below.
Εἰ γὰρ ἐγὼ λυπῶ ὑμᾶς,
καὶ τίς ἐστιν ὁ εὐφραίνων με, εἰ μὴ ὁ λυπού-
μενος ἐξ ἐμοῦ; Ποία αὕτη ἀκολουθία; Μεγίστη μὲν
οὖν. Σκόπει δέ· Οὐκ ἠθέλησα, φησὶν, ἐλθεῖν πρὸς
ὑμᾶς, ἵνα μὴ λυπήσω ὑμᾶς πλέον, ἐπιτιμῶν, ἀγα-
νακτῶν, ἀποστρεφόμενος. Εἶτα ἐπειδὴ καὶ αὐτὸ σφο-
δρὸν ἦν, καὶ κατηγορίαν αὐτῶν εἶχεν, εἴ γε οὕτως
ἔζων ὡς Παῦλον λυπεῖν, ἐπιδιορθώσει χρώμενος, φη-
σίν· Εἰ γὰρ ἐγὼ λυπῶ ὑμᾶς, καὶ τίς ἐστιν ὁ εὐ-
φραίνων με, εἰ μὴ ὁ λυπούμενος ἐξ ἐμοῦ; Ὃ δὲ
λέγει, τοιοῦτόν ἐστιν· Εἰ δὲ καὶ ἐν λύπῃ ἔμελλον εἶ-
βʹ. Καὶ ὅρα σύνεσιν. Ὃ γὰρ τοῦ νόμου τῶν μαθητῶν
ἦν, τὸ ἀλγεῖν καὶ αἰσθάνεσθαι ἐπιτιμωμένους, τοῦτο
ὡς χαριζομένους αὐτοὺς εἰσάγει. Οὐδεὶς γάρ με οὕτως
εὐφραίνει, φησὶν, ὡς ἐκεῖνος ὁ ἐπιστρεφόμενος τῶν
ἐμῶν ῥημάτων, καὶ λυπούμενος ὅταν βλέπῃ με ὀργι-
ζόμενον. Καίτοι τὸ ἀκόλουθον ἦν εἰπεῖν. Εἰ γὰρ ἐγὼ
λυπῶ ὑμᾶς, καὶ τίς ἐστιν ὁ δυνάμενος ὑμᾶς εὐφρᾶναι;
ἀλλ' οὐ λέγει τοῦτο, ἀλλ' ἀντιστρέφει πάλιν αὐτὸ,
θεραπεύων αὐτοὺς, καὶ λέγων· Εἰ καὶ λυπῶ ὑμᾶς,
χάριν μοι παρέχετε κἀν τούτῳ μεγίστην, ὅτι δάκνεσθε
ὑπὸ τῶν παρ' ἐμοῦ λεγομένων.