Husband going out for a guys night

My husband told me next weekend he got invited out to a guys night by his coworkers. They go out from time to time. He's only been at that job three months. My husband has never had friends and I honestly dropped my friends when me and my husband got serious. I don't need to just hang out with other women. Most of them are gossips and just shit talk each other anyway. How I see things my husband is my best friend and the ONLY friend I need. I also feel like when you have friends it puts your marriage at risk and it's best to protect your marriage at all cost. My husband died feel the same way... I told him all this and he said he would like to have friends because he never got friends before. I don't understand why a grown married man needs to friends or a guys night. When I asked if I could come he just did the point is it's a guys night. I'm not sure what to do. Maybe I sound crazy but I feel I'm supposed to be his best friend.