"Should i be worried if my boyfriends ex still likes him, and they hung out today?"

Right now it's normal to be a little bit worried/jealous/confused but don't make assumptions. Accusing your boyfriend of things will just make him feel like you're being controlling and that's a major turnoff for guys. It will also just prove to his ex girlfriend that you're threatened by her which is never a good thing.

However, if this becomes a habit, and you feel like it's getting sketchy and you do have a reason to be mad then confront him about it. Do not automatically accuse him though, that will just show that you don't trust him. Unless you have proof or evidence then accuse all you want.

But for now, don't worry too much. There's a good chance they're just friends, even if she wants more than that.