You sound very jealous and controlling. If you carry on like this you won't be married much longer. Your husband has done nothing wrong.
People have a wide variety of interests and it's next to impossible to find someone else with exactly the same interests. I have a friend who is a married woman, she talks to me about politics because her husband isn't really interested in it. Similarly I talk to him about the local music scene because she's not into that.
There's nothing romantic or untoward about our meetings, we're just friends meeting up to chat and discuss common interests. That's what normal people do.
You said your husband talks to others about gaming. I imagine he's more into it than you are and is just sharing something with someone who will appreciate it instead of just putting up with it.