Unlike child support, spousal support is often very difficult (if not impossible) to modify after the divorce is final, so getting it right the first time is a must!
You are establishing a status quo that says that you can pay alimony by paying for both places. Move back in, If he assaults you , call the police and get a restraining order.
Which means you get the house. And he has to find somewhere else to live. And he will have to file for support to get you to pay anything.
Right now, if you stop paying, your credit is wrecked.
If you choose not to do this, then only pay the mortgage and any credit cards that are in your name only. Let him pay for everything else.
One thing to keep in mind is that any debt that he incurs before you file for divorce will be considered joint debt. Which means that if he charges $30,000 on a credit card if you decide to wait a year to file, you are on the hook for that.
As for his being willingly underemployed, you can ask that income is imputed to him based on his college degree and what people with that type of degree make in the area that you live.
And if you do get stuck with alimony (which is likely with the huge discrepancy in income), I would try to make it a condition that should he get that inheritance it stops, has a time limit and that co-habitation (with either gender, roommates count)/remarriage means that it ends. And if he doesn't disclose when it happens and you continue to pay alimony as a result, you will be reimbursed what you paid as soon as you prove when he either inherited the money, acquired a room-mate or remarried.