Not sure how to feel

Ok so me and my boyfriend have been together over a year now and got engaged this last December, while I know it seems fast we have been best friends since we were in second grade and are now in are late 20s. We have both been threw some crappy relationships and I was previously married and have a 5yr old who my boyfriend loves dearly and my son loves him even calls him dad. Now for the part I'm not sure about, my boyfriend is into pegging while a bit kinky I don't mind it because we both enjoy pleasing each other but what's got me worried is I have now caught my boyfriend twice now posting personal adds on Craigslist, the first time was when he was working a job out of town with a friend. I confronted him about it and he was genuinely upset and appologettic said nothing happened and promised it would never happen again but it has happened again at the beginning of last month he did another post this time looking for a male companion, he talked to a few people but says that's as far as it has gone and that he hasn't cheated on me ,he deleted the post and all the emails right in front of me and once again apologized. I want to believe him but I've been hurt in the past when my son's father cheated on me and I don't want to go threw that again and my boyfriend is nothing like my ex was and with the exception of the post's everything has been going wondfuly, I now check his phone almost regularly to make sure he's not doing anything and I hate being like that but I'm still hurt and not sure what to do I really do love this man and want to marry him but I don't know if I can completely move Past this.