Just confused, lonely, and over it....

So...I have been with my SO for just about 3 years. Or relationship started out a little weird we dated in college for a while but broke up...and almost 3 years later we got back together. I had a daughter which he knew of in college and but I was pregnant with my son then. My kids dad had just died and my SO reached out to me.

My kids dad died in 2012. At the time my kids dad had cheated on me and hurt me so bad at the time of his death I was happy to move on from a terrible relationship ( sound bad I know) so I told my SO I was cool with moving on. Granted I did have other guys that were still trying to talk to me then so I flirted with them but nothing serious.

Fast forward to now....im currently 38 weeks 4 days with my 3rd (my SO 1st)...Like all of a sudden like we live on one side of town but your from another and you decide you would rather be there until 3-4 a.m. He seemed different to me so one day I go through his phone. Turns out he is talking to girls via fb and text. Like seriously??? He knows EVERYTHING my other 2 kids dad put me through and it was alot we had an understanding we would never do that we would just part ways if we weren't happy And here you are sexting a girl on fb and calling some other girl baby talking about picking her up from work and stuff. Needless to say I confronted him and he swore hew was sorry and it would never happen again.

Now I look again and guess what?? Still talking to the girl and your excuse is you like the attention you get and you have a problem you don't want to lose your family you are sorry. You love us and don't want too lose us WTF??... I don't understand like....I have literally held down the fort while you didn't have a job, (he had a good one now though) I basically took care of you when you had no one else to turn too.... I think I deserve more then some lame ass excuse....