Feelings for someone else

So my bf and I just had a daughter she’s almost 4 months and this guy that’s been hanging around my parents house (missionary) has been making me laugh like a lot. What started out to be nothing kinda turned into something for me. My daughters father is such a great guy to me and his daughter. He took care of the both of us after I had a c section. But after being together for almost 3 years it’s like we stay together as routine. This other guy makes me laugh and in a way I can sense he developed feelings too but out of respect for my bf he doesn’t cross any boundaries. We’re not flirty but respectful and like we both can sense it ? Idk . I feel horrible because I love my bf and he’s been a great person to me.