Should I dispute a trademark application that is identical to a domain I own?

Over 25 years ago I bought a pretty generic, banking related domain name, and I recently had someone contact me about buying it. We weren't able to agree on a price and they eventually bought a different domain name, somewhat similar to the one I own.

Recently I found out that they had already started to trademark the same name as the domain name I own, and which they we're trying to purchase.

1. The business they are starting has nothing to do with banking. It is an online casino.

2. Essentially, they were negotiating in bad faith since they had already applied to trademark the name before contacting me to purchase the domain.

3. They are located in a European country and are filing with the European trademark agency.

4. I live in America.

I have a few days left to dispute the trademark and I'm wondering if it's worth the money.

Once the name is trademarked can they try to take the domain name based on the trademark?

Just wondering what I should do here.