Oh, so that is the cause. Lets address some things here: 1 for those situations is why you go out in boys night, to ask the opnion of other guys. when you are stressed and worried, its normal, and she may are doing it.
2 You have to talk to her about it, make she knows what are your concerns, and to know what is going on. This is the most important part. Also you gotta be aware that,for you, you are the most important person and be confident with who you are. If she doesn't want you, bad for her.
3 it is orange code that she is looking the facebook of this guy. WTF do you mean by SHE WAS SLEEPING WITH ANOTHER GUY WHILE PREGNANT? Does she talked to this guy? Also those photos are stored in her phone, or are photos of her exs alone?