You have received some really good advice here. I would listen to it even if it's not easy advice to take emotionally. People make their choices like GF going back to her abusive ex. The choices we make either work or they don't & we have to deal with the consequences good or bad.

Don't waste your time waiting to see what the consequences end up being or hanging around to give her support from the side line to keep a door open for her. Commitment to go back needs to be commitment to make it work without an ex BF on the side line.

Get on with your life & don't wait around to see what the consequences might be. If it's her choice to go back to him, that means she still has feelings for him that she doesn't have for you.....good time to just make the break & leave it at that.