A lawyer will have to review your contract. It is possible to file suit to enforce arbitration.

You have no grounds for a lawsuit under these facts IMO.

Can my ex get part of my retirement after final judgement ?

This is too complicated an issue to be resolved in this forum. Hopefully you had counsel for your divorce. If so, contact them. if not, you need to...

At 18 you are an adult and can live where you want.

The cost of any such lawsuit would far outweigh any potential recovery.

You can retain counsel to send a Cease and Desist letter. While legally unenforceable it at least let's them know you are serious and will pursue it.

Lawsuits are time consuming and expensive. Better to resolve with your insurance carrier.

Two issues: Does this violate state law? Some states prohibit such recordings. Does it violate school policy? That will depend on the particular...

The cost of suing her would far outweigh any potential recovery, but you should call Animal Control.

In my experience (I did the same thing) I canceled the order through PayPal and they handled it through their dispute resolution process.