Very sticky

For some time now I have had a strong feeling that my SO has something going on with one of his guy friends, he's told me that his guy friend ex had also felt that there was something going on between them. When he goes over his house they are completely alone. He's told me an incident years ago between them another guy and a girl that just didn't make any sense what so ever. I'm currently pregnant with his child , it completely scares me for that matter that he's possibly lying and cheating with the same sex. Could it possibly be me thinking he's in the closet because I'm actually the one that's in the closet? I'd appreciate if all negativity be kept to yourself.