I suggest that you both try to resolve this as amicably as you can.
Your (ex?) boyfriend is very vulnerable financially if what you say is correct. His name alone is on the debt secured by the house you own jointly. He doesn't even live there, and he is depending on you to make the payments on time so that he doesn't go into default.
You could be vulnerable as well. I don't know how the deed is written up, but he may be able to force the sale of the house because he's co-owner, in which case you'd need to find a place to live. That, and he's currently getting half of the equity from your mortgage payments, while paying nothing. (You are living in the house, though.)
Assuming he doesn't mean any ill will, if you can get an agreement in writing that protects both your interests in the matter, I'd think that would be far better financially than getting someone to protect your own interests (and he his own). Lawyer fees tend to go up if the two parties are fighting.