advice needed!!

so awhile ago I caught my husband msging another woman... i got really angry and upset, and I know its no excuse but he was going through some really hard times! (he was held up at work) and I thought I was over it. But now Im pregnant and nearing the end (36 weeks) and I have soo many mixed emotions. I know I can trust him but I feel so insecure. he has been snapchatting another woman... and honestly it bugs me. Ive told him how I felt and he deleted her but then I discovered he was still doing it! (we were talking and looking at something on his phone when he got one from her. he very quickly hid his screen and this is what makes me even more suspicious because it was like he was hiding it from me. we had an arguement and he said he re added her because she kept msging him and got annoyed he deleted her. but shouldnt he put my feelings first? my annoyance that he is still talking to her! he said I shouldnt be upset because she is engaged. but he was MARRIED when he was msging the other woman and that didnt stop him. i guess Im just at a loss as to what to do. I love him. but with all my hormones, I am really struggling to keep it together. Am I being to hard on him?