That's a lot of stuff you're going through and that sucks. In my previous position with my company, I dealt with people and their credit history every day. You can't imagine the stories I've heard about people's credit getting all screwed up.
In my opinion, DON'T DO IT!! Let's say you guys don't get back together. You will need all the financial positives you can get. The last thing you need is an Auto Chargeoff or a Repo on your Credit Bureau.
I know you're at your lows right now but you have all of us a click away.