I'm going to ditch my friend in an abusive relationship
Isn't there a better option than just ditching him?
He also requires the support of me. If I leave him, he's screwed.
It's not nice to let someone down when they need you the most. You should be there to support your friend.
But when I needed him, he ditched me.
Don't you think your friend is in a very sticky situation right now? He really needs you, and his past problems might have been affecting his relationship with you. Perhaps it's best to listen to him, so you can understand why he did such things.