Keep having dreams my boyfriend is cheating

I don't know why but it makes me feel physically sick when I get up. He's never done anything to make me believe he would ever be unfaithful, he's such an amazing man, and yet these dreams keep coming. And I feel so insecure and worried now that maybe he could be cheating and I wouldn't know because he's really good at hiding it. I get jealous whenever he's with a friend that's a girl even if it's like a long time family friend when I have no reason to. i mean I obviously don't say anything but I feel like my own mind is killing me. We've been apart for a month now because I was home far away visiting family but I go back Monday so hopefully things will be back to normal. Does anyone else have these dreams? How do you deal with them? I never used to be this insecure before getting pregnant