Woops

My ex of half a year( sadly longest relationship) cheated on me hence ex and I started talking with his best friend just as friends and now a year later his best friend and I are dating and he was my first.. he uses this as a reminder to both of us that everything happens for a reason. I love him more and more every day. Him and my ex aren’t friends anymore. He doesn’t agree with a lot of things my ex did and so they cut ties. I feel stupid saying I feel in love and trying to plan a life with him because when I did that with my ex he cheated. It’s a completely different thing I know but it’s just so scary. I just jumped headfirst into the ex relationship... I actually built this one based on feelings and he just makes me laugh and feel strong and happy and so sexy and loved. Am I making a mistake? Idk what the mistake could be but I’m scared.