Is the divorce final yet? There should be a clause in it that addresses the house issue so that there should be no entanglements. It is never a good idea to have any such joint financial dealings with your ex afterwards.

Judy: In many cases, the marital home is sold. The other poster "Blue" is right. Info. about the house should/should have been in the divorce agreement. Your Lawyer should have addressed this if you have one.

Thanks Blue and Lara:

I do have a lawyer and when we served him with papers, we also served him with a copy of our proposed settlement agreement because we had agreed to settle out of court. He is now not agreeing to the 70/30 split and this is why we are stuck. I was going to stay in house until sold while he didn't contribute to mortgage. Mind me that he's stopped contributing in the past as well. My frustration is that I've been told by several attorneys that I deserve a credit for amounts owed by him and this is why I offered him this percentage. His lawyer is telling him that it doesn't matter if he stopped contributing at some point and that he is entitled to his share regardless. Does that seem fair? I've basically been the sole provider because since I earn more than him (not much more), he took advantage of that and passed on the majority of the responsibilities (financial and other) to me.

Most states these days stipulate that divorcing spouses split marital assets and marital debts more or less evenly unless they agree to different percentages. Basically, anything acquired during marriage is considered marital, regardless whether one person paid for it or not.
There's a small number of situations otherwise, like infidelity, but the bar for proof is high.
Assuming more of his debt is a good negotiating tactic but you say he's not cooperating.