Legal Question in Civil Litigation in Michigan

Re: Ex fiancee in posession of house and car.

Hmmm!

I think this is really HIS concern, but...

in many states, when you have prenuptials taking property together, and one person (here, the man) is clearly the one who contributed the capital to acquire the asset, then a court acting in equity(that is, "fairness",--the court must have jurisdiction over the real estate, so it must be a local court) may have the power to declare that any interest she had was a revocable gift in anticipation of marriage, much like a wedding ring.

She may have some legal interest in the property, if she made improvements to it, but he should be able to buy her out if her interest is found to be small.

File an action to have the title "quieted." Same thing with the Mercedes.

Once done, he can have his ex-fiancee evicted...but it doesn't sound like he really wants her out of there, if she's still there after they have supposedly broken up.

I am sceptical of your characterization of her as obsessed when HE is the one failing to protect his interest in the property. Caveat emptor.