In divorce agreement it states that spouse has exclusive use of marital homeplace. What if no date was set for how long? And spouse has remarried. Mortgage is in non-custodial parents name and deed is in both parties names.
I am guessing that you made what is a very expensive mistake and did not have legal counsel. A lawyer would have indicated what ultimately happens to the home. If there is no time limit, although I'd have to read the paperwork, it likely means as long as she lives. Show it to a lawyer now, but it is very possible you made an expensive and unfixable mistake.
Without knowing more and reviewing the agreement, it appears you failed to take care of a very important issue at the time of the divorce. A provision should have been included wherein your ex had a certain period of time to remove you from the mortgage or place the residence on the market. If there is no provision on how or when to remove you from the mortgage, it was a very big mistake at the time of the divorce. I suggest you have the agreement reviewed by a family law attorney.