"Time to stop being so ridiculously selfish and just concentrate on what is absolutely best for him. For now, that means keeping his dad in his life as long as Gabe's nuttiness is not hurting Marc. He doesn't show any of this to Marc, he acts totally normal with him, so I'm not concerned about it. That could change, but for now it's ok and Marc likes having him here."
Now I think you are lying to yourself. Gabe is there because you aren't done. If you aren't done, you may as well try. Work on boundaries, work on being direct, work on taking care of yourself.
