Coparent advice

I have a protection order against my ex partner and father of my son. He sees him every Sunday for a few hours, drop offs and pick ups happen with my dad so it’s no contact. Anyways a few months ago his brother got out of jail for almost killing his ex partner and multiple drug charges. I have said our son is not to be around his brother & he agreed. Anyways on Sunday our 3yo son told me he saw Uncle & his cousin they played together. I raised this with my sons dad & he completely denied it, saying his brother wasn’t there just our sons cousin. I told him I don’t believe him, and that if he wishes to see our son it will now be supervised at a park because I don’t trust him & fear for our sons safety around him. He told me to stop thinking of myself and stop having an ego and that this is wrong of me.

I just want to know if I’m doing the wrong thing? I genuinely don’t feel comfortable sending my son over there and him being around his uncle even though his dad is denying it obviously our 3yo can communicate. Please help if you’ve been through similar. I have a meeting with legal aide in 2 weeks