May be both of you should go see a psychologist / social worker together. May be your husband didn't do anyting but you cannot get pass this 心結. So go get help before this 心結 balloon into a much bigger problem.
Don't get too negative la. This is not your fault or your husband's fault; he already proved "真系無菌" ma. Good luck to both of you
This is a very serious issue between you and your hubby. You need to address it immediately.
First of all, you have to learn more about the virus. As it can be transmitted by other means (other than intercourse).I think you should trust your hubby and try to get pass this isuue.
Instead of accusing your hubby for being unfaithful, he can also accuse you for being unfaithful to him as he has been tested negative (he does carry the virus). If he has the trust in you, then it is not fair for you to keep thinking of this issue.