I made $1000 from selling my husband's ex's belongings
Did he agree to let you do that?
I didn't ask him.
That's awful of you!  You can't just sell someone's stuff without asking them if it's okay.  That might land you in jail!
It's his fault for dumping me  It's a good thing I didn't touch his savings!
Now look, you know those things weren't yours. You did a deliberate act by selling them without his knowledge. He has every right to sue you.