Re: Finally pregnant and he is acting weird.
Hi, I am sorry you have gone through so much as it is, and this to top it off.
I can't help but wonder if your husband is feeling very insecure - about his "potency", his "manhood", because of the fertility problems he seems to have - and that is making him insecure about how he could possibly impregnate you. IOW, maybe he is thinking it's about impossible for him to impregnate you, so "it must be someone else"?
Have you simply tried talking openly to him? I don't know what he or you are like in behavior normally; you would know how that might work or not. You can give it a shot, though; approaching him and asking him if he's simply in disbelief that he could've himself gotten you pregnant. And assuring him that even if it's a 1-a-million shot, it can still happen!
If you don't think you can each talk civilly together (don't be surprised by a few tears or defensive remarks; I mean a real shout fest or shut-down), do you have any pastor or counselor or anyone you can talk to together about this? (If public, you might want to consider asking by yourself 1st, then inviting DH in.) Do you have any friends or more-distant relatives between you that are fair and could help you discuss these things he's worried about?