Hi, I have to chime in to agree with Trek. If you do not know that your significant other has only been with you, then you owe it to yourself to be tested for the gamut of STDs. I'm so sorry for your situation. I agree with others that I have known people in 'open' relationships. I couldn't be in one myself, but that's just me. The key to an 'open' relationship is that BOTH partners know about the openness (otherwise, it's cheating), agree to guidelines, and have safe parameters. Without these in place, the "openness" is just what I said above, cheating. I too would have a hard time trusting, but at this point, protect yourself. I wouldn't have unprotected sex with him any longer, and I would begin setting money aside as well. Begin to disentangle your finances from him. When I was in a heartbreaking situation, I put my horse in my mother's name so he wouldn't try to take her, and I began to establish accounts under my mom's name too so that he couldn't claim access to those accounts. I do not know whether or not these things would have helped if it had gotten really nasty with him, but it did give me some peace of mind. I'm so sorry. You will get through this - just take it a day at a time...