Help I need advice! Please.. :(

First things first I apologize for the long post! My boyfriend and I just found out last week were going to have a baby after two miscarriages. He was looking for his charger before bed, and when I got up to go pee I found it in the bathroom so I brought it upstairs with me and plugged his phone in for him since he was sleeping.. When I did the screen lit up and he had a fb message from "brikelle" (one of his exs) so like any other girlfriend would I opened it and said are you still up we have to finish our conversation.. Looked through the rest he did not mention at all that he was with me and that he was expecting a baby with me, she kept saying she needs to "run" into him sometime, she misses him, blah blah blah I stopped right there I couldn't continue to read anymore. I also seen a message from another ex but couldn't open that message due to me sobbing already. So I woke him up and asked why he was talking to Brikelle, he then started yelling and cussing at me saying I shouldn't have been going through his phone. So I grabbed my pillows and came down stairs then I get texts from him making me feel like complete s***! I can't get too stressed I can't lose this baby too :'( I need some advice please.. Thank you everyone in advance for taking the time to read this.