Being cheated on often is a slow motion train wreck till suddenly undeniable evidence presents itself. then it all crashes at once.

The anxiety and feeling of something being wrong, the oddities and inconsistency that drive you crazy thinking you are paranoid, they sometimes have a solid foundation but lack evidence to back it up.

and much like a train sometimes can sneak up on you, it can suddenly in an instant hit you with 18,000 tons.

source: Happened to me, took a couple months to burst and find evidence founding my anxiety and fears.

It's almost a relief to find evidence of it, because at least you no longer are chewing away at yourself over all the blatant signs without having any UN-deniable proof. Being treated like YOUR the crazy one causing problems, all the while being betrayed and lied to right to your face on a daily basis.

This post certainly has all the tell signs of the bad news, but of course the only thing OP can do is have open and honest conversations about these concerns like an adult, there are reasonable expectations that are not being met, and given the history that's know.. it's more than fair to request evidence of a paternity test, should it come back positive it makes this more anxiety and fears based on what doctors said is impossible. and should the test come back negative, then it's time to be adults about the problem and separate.

It's emotional hell. But dragging it out to deal with later, only makes the pain cut deeper. Specially if the child isn't yours and you find out a few years down the road when you're now "daddy" to this other person's child and that's one extra life you're tearing out of your heart, and theirs.