I'm not a lawyer, so this isn't legal advice. However, if the husband doesn't keep current on payments (whether or not the house is in his name), kick him out and foreclose. It's unclear from your question whether both the husband and wife are on the mortgage. If he's not on the mortgage, then kick him out and foreclose now. Otherwise--and consult with a lawyer on this--he may argue that he's a tenant and thus protected by provisions applying to tenants.
Again, I'm not a lawyer, but DO NOT WAIT UNTIL ANY DIVORCE HEARING. That has no bearing on your situation. Your situation is that the wife (and maybe the husband) agreed to pay you for the purchase of your house. If they're not paying, they're in default. And divorce proceedings could stretch on for months, maybe even years. You might find yourself in a situation where you couldn't evict the husband and yet have no income from the property and be unable to sell it to anyone else.
So: Check with a lawyer. And deal with the situation now; don't wait.
Hope that helps.
Since you used a lawyer to write up the contract, you should get in touch with
The lawyer and start foreclosure proceedings at the earliest.
Right you can otherwise choose to wait for divorce proceedings to settle that can take
A year, while you do not get the funds that you are owed, and if the husband cannot make up the
Difference then rightfully he has got concern of loosing the house.
There likely are not much choices here, there is already a breach of contract and the more you wait the
More you loose.
Call your attorney and do the needful. Good luck.