Dear Blue ocean~
Welcome here, and I'm very sorry you are in this situation. You are sounding at the end of your tether and something really needs to be done right now.
May I ask if you have talked with your husband abut this? Without knowing that -and his reaction -it is hard to say that much.
You do love him so I guess in an ideal world the matter could be patched up - do you think that is possible or has it gone too far? It sounds as if his current mates are not a good influence.
Relationships Australia (1300 364 277) is a good first stop. They are very used to these sorts of situations, can advise alternatives and maybe get the pair of you to counseling if you think that appropriate
On a practical note I'd suggest you visit oyur GP in relation to STDs.
I look forward to your coming back and saying more