Should I Be Worried?

My bf and I have been together for 7 months. This is my first serious relationship and this is his third. About two years ago he was in a 3 year relationship with his high school sweet heart. My bf and I are long distance so we talk on the phone every night and fall asleep over the phone... one night I over heard him talking to his brother about his ex (I guess my bf thought I fell asleep lol)

He was talking about heartbreak regarding his ex... my bf said “heart break is the worst”, his brother responded “yeah, but u seem alright now”. My bf said “what makes u think that? That’s what I want u to think”, his brother responded “well u can get her (his ex) back if u wanted”. My bf said “its not that easy”.

Idk why this hurt my feelings lol. It made me feel like I wasn’t making him happy and he still thinks about being with her. Am I overreacting? Should I even be worried?