Actually, that $10,000 will likely be joint debt, as well as any other of his expenses, including those for outings with his GF.
I guess it depends on the state (and the judge), but that's very different from everything I've ever heard. "Squandering of marital assets" is usually not looked upon too kindly by a family court judge.
Puppy
That would be nice, but it certainly isn't the case everywhere. When I got D, I had roughly $10,000 in old debt in my name that we had jointly incurred while married. XH had roughly $10,000 of brand new debt, including a new car for his GF. Unfortunately, we were still married while he racked up those charges, so it too counted as joint debt. So, it "balanced out" legally. Yeah, right.
It can't hurt, though, to get your name removed from any joint credit accounts and to tell them that you won't be responsible for further charges. And, I think a legal separation can help stop the joint debt accumulating in some cases.