Yes, absolutely get a lawyer! Who cares what your stbx thinks of it, or what it might "look like" to him. I would give precious little consideration to a "man" who takes your/your child's money....
: I don't know your entire story, but I do know that regardless of who left, you are not responsible for supporting this man!!!!! You are, however, responsible for your child, and I simply don't see how you can take care of your child, if you are giving your money away to this man!
If you're not going to stand up for yourself and your child, I hope that a lawyer will do that for you. You don't owe that leech a thing.

If you're not going to stand up for yourself and your child, I hope that a lawyer will do that for you. You don't owe that leech a thing.