Little background before I (m24) go into the situation. My friend (m24) and his wife (f25) have had a rocky relationship. About a year ago he was venting his frustration with her about her pinching him on St Patrick day, which is his birthday. He was in a discord call with me and a couple friends. He threatened to hit her and acted like it was an okay response to have. I called him out on it and the friend group decided to distance ourselves. The situation came to a head when his fiance at the time decided to forgive and defend him and dismiss our concerns. The rest of the group kept their distance but remained friendly with him. I however set the boundary that I wouldn't seek a friendship with him or attend his wedding unless he went to therapy. A year passed and his behavior drastically improved and he is genuinely a better person. He never sought therapy however, which he gave me his word he would. I decided that however painful it would be I'd keep my promise and not attend his wedding. He hasn't given me any grief over this but the rest of my friends have. AITAH?

Edit: Clarification