C.M.
You should feel good about this. You have obviously picked a good roll model for your boys, and thats important. If I was your boyfriend I would be proud to have them call me dad, and to know that they except him as their second dad. I came from a split up family also, when i was a year and a half my dad married my step mom. I have to say she has been more of a mother to me then my own. I also have two step children, and I have been helping raise the teenage daughter for almost four years now. She doesn't call me mom, but sometimes it slips and she does. It feels good.. I know I will never take the place of her mother, but to know she cares, well that makes it all better. I don't know if this helps but Just let your boys decide what they want. Happy holidays
chris