Ye took to Twitter Saturday with the apology, writing ... "I would like to apologize to my wife Kim for going public with something that was a private matter."

He continued, "I did not cover her like she has covered me. To Kim I want to say I know I hurt you. Please forgive me. Thank you for always being there for me."

TMZ broke the story ... Ye had been giving Kim the cold shoulder as she tried to reach out to him to get him the help he needed -- this after he lapsed again into a serious bipolar episode, hurling a barrage of disparaging tweets that took aim at her, her mom, Kris Jenner, and others in the family. He even said he'd been trying to divorce her for a while now.

What's confusing ... specifically which comment he's apologizing for, since the mea culpa is in the singular -- "something that was a private matter."

Ye said a lot, but it would seem the most hurtful comment was last Sunday in South Carolina, when he said he wanted Kim to get an abortion but she would not and had the baby anyway. There were other things too -- allegations of cheating, etc., but it sure seems the abortion talk was the most hurtful, and one thing we know ... Kim's protective of her kids.