Why am I feeling very insecure, I can't control my feelings :(?

[L]

To start off with I am nearly 7 months pregnant, so am thinking maybe my hormones are getting the better of me, second of all my partner hasnt helped me from not feeling these feeling's. The pregnancy came as a shock as I was told I couldnt have children, so this pregnancy was and is a blessing for me although its been one long hard road throughout. My partner demanded I got an abortion, there was no way I was going to get one ( I am not against abortion at all by the way), it was a struggle keeping positive, he eventually accepted the pregnancy and has attended the scan's so I put his actions down to shock at the start. 4 months into the pregnancy I had a feeling something wasnt right, I did check his mobile and wished I never, he had girls txting him and some pictures of them also, this led me to check his facebook account which led to me finding him chatting another girl up asking her to call him as he hardly used his facebook account. This made me sick, ive been very loving, honest and devoted in our relationship (we have grew up together since the age of 10 and have always been best friends until last year) I have never felt so very insecure, I fronted him with my findings and told him I wouldnt accept any of this as I am worth more than that and I have the pregnancy to focus on. To be honest it crushed me inside out, ive never felt so hurt, even more so because he was my best mate not only my partner. He started going to his ex partners (they have a 6 year old daughter together) and staying there till 1am or when ever, I love his daughter and there isnt a thing I wouldnt do for her but I didnt like him spending all these hours at his ex's when shes always seen our home as her second home, turns out his ex had told my partner she didnt want his daughter at our home as she was feeling insecure about the relationship me and my partner's daughter has ect, she had a party at her home and I was invited and his daugter was over the moon I turned up but her mum didnt like her daughter saying her birthday was much better since i'd turned up (I titally understand it would hav eben hurtful to hear). I felt hurt by this as i'd rather have a woman that adores my child then choose to keep the child seperate ect. Now am 7 months pregnant into the pregnancy and am sinking even more, he's hiding his mobile and he's back on facebook till silly o'clock. I am really at the end of saying am no door mat I deserve much better and so does my unborn child, I just don't know if it me or if I have reason to be feeling very insecure right now, its all about loving and trusting and hands on my heart but my mind is telling me to finish things and walk so this doesn't turn to hate for the sake of my baby.