First, I'm not sure you're describing OCD. Everyone on here wants to have OCD. Not every obsessive thought is OCD. All mental illnesses involve obsessively thinking anxious or depressed thoughts or nobody would have depression or anxiety. In your case, you seem to have a whopping case of anxiety of whatever type it is and probably depression. You say you talked to someone -- does that mean you had formal therapy? Was it with a psychologist who specialized in treating people like you? Did you give it some time? Did you try a different type of therapy until you found one that worked for you? To me, it sounds like your husband is being sarcastic. And if you know anything about video games, women are few and far between on them, so unless you suspect he's gay, no, he's not meeting women playing video games. Quite the contrary, video game addicts have a reputation of having a hard time finding dates, it's a comedic cliche. But reasoning isn't going to work because you're thinking irrationally. Might he be cheating? Of course, people do cheat on their spouses. You might cheat too. It's very common. Is he? Not if he's home all the time playing video games. We can't talk you out of having an anxiety problem. For that, you need a professional therapist, and if you can't find one you're willing to do the work with then you might need medication, because if this is your life it's driving you nuts. Maybe you're exaggerating. I have a really bad anxiety problem, but even I would get sarcastic if my wife kept asking me if I was cheating. If I was, I wouldn't admit it, and if I wasn't, I'd wonder why she thought I was too. Wouldn't you? Again, I'm being rational here, and your thoughts are the problem. Because yes, people do cheat on each other. Not usually in their own homes, though. So you're not going to guarantee that ever, you're just going to have to trust until your trust proves to have been wrongly placed. If it has been 10 years, you've objectively got a stable relationship. But you don't have a stable thinking process, so while you'll never control human beings and the dumb things they do, you might be able to stop making yourself miserable. Peace.
Sounds irrational, yes. Sounds anxious, yes. Constant fear of germs being ocd? Could be. Do you see a doctor?
I think you need to get some help professionally with this. I also think your boyfriend has a problem. Video game can become an addiction and staying up all night to play? I'd have a REAL problem with that. And it sounds like perhaps he doesn't work? What is he bringing to this relationship? I'm of the belief that this is also very unhealthy behavior. You deserve an equal and gaming day and night is not a true partner. That's a child (my teens try to do that and CAN'T because I set a boundary but also because they have too many responsibilities. WHERE is your boyfriend's responsibility?)
Do you see a therapist or anything? Do you have any insurance?