Just a thought... but it may not be the fact that you are apologizing that is making you feel bad. It may be the WAY you do it.

Including your entire mental health history, especially to a stranger, in an apology is self damaging. You're not taking care of yourself when you do that and it feels bad.

It's entirely ok to just say something like "I apologize for my behavior, it was inappropriate, and I'll try not to let it happen again." And just leave it at that.

AS to why you feel it necessary to include your MI issues, it could be that we as a society are programmed to need an excuse or reason to do or say something harsh. But sometimes stuff just happens.

We all make mistakes and say or do something that is "wrong" for whatever reason. You don't need to drag out your inner life and lay out on the table.