Ex making me doubt?

​So here's the thing. I have been with my boyfriend fr a few months now. Lately, my ex got back in my life, i started doubting about my current relationship but ended up letting it go. The thing is, we used to see each other every weekend, now it seems I don't care anymore wether I see him or not. I have seemed to be very happy.. Without him. Met a few new people and smile won't leave my face when I'm around them. Thing is, i am terrified of hurting him. Advices?