He tells me what he thinks I want to hear

Okay so my partner and I have been together for almost five years off and on....his mom tries to break us up, but he plays all sweet to your face. I didn't know she disliked me until the last time we broke up and then decided to try to work it out. I use to confide in here with our problems only to find out she was turning around and telling me I want to kick him out and that I wanted to end it. Then just before we decided to try to work it out after being apart for 4-5 months, I asked him if he had been with anyone else while we were apart (for sexual health reasons). He said no that all he did was think about me and our boys (3 kids), and that everything reminded him of me. I beleived him...until, our middle child got his cell phone, and the contact list was up, that's when I see HER number....then after he moved in with me, one night he had made plans to do dinner with the family and once the two younger boys were in bed we were going to play a board game with our oldest, and then when he went to bed we were going to watch a movie...the he got a text, and all of asudden it was soo important for him to leave town to go get his stuff that was a week ago of no importance. I told him that something doesn't add up and that I was not comfortable with that, he blew up, went to the wasroom, I checked his phone and he had a message from here sayin that she doesn't want to loose what they share, that she is confussed and so sorry...I took it as, well obviousely he ended what ever was going on and wanted to be with me, he left everything behind in the city we use to live in....his phone was cancled, and I felt things were good and getting better...until he started talking to his mother again. Then he out of no where decided he was going to go back home to visit family and friends for the weekend, and I told him that I found a sitter and that we should both go, it would be nice for us to have some time without the kids. He flat out told me no, that he doesn't want me or the kids there, that he just wanted a weekend alone. Then he left for the bank and forgot his new phone mommy dearest bought him so they could text each other, and sure as sh*t, he had a text from HER saying okay, I'll make it a double...I confronted him on this he became really angery, told me he didn't give a f*ck what I thought or how I felt he was going to go anyways, then he left. So I guess what I'm asking is, what opinions are out there as to how to handle this or what to do....I do love him with all of my being, but I want to feel important, I want my other half to want to spend time with me, and I want to be able to trust him....I'm so confussed