Like the rest have said non of this matters.. If he cheated he cheated

But and this might sound weird how sure are you they slept together?

Because sometimes men especially if they served together can be pretty "gay" on text etc but it's all a joke

But you did mention you've been having less sex so I'd say trust your self

Anyways it seems like he cheated so gtfo or better yet kick the mf out you deserve better so please if he really cheated don't give him another chance