Actually in every relationship transparency and sharing of secrets are keys to a strong bound leading to better understanding between the two, but when you have a spouse that's somehow judgemental at almost everything, you will surely be unwilling to reveal certain personal things about yourself to them especially gambling that is being vilified by many as something bad.
She felt insecure about the man, first he joined hands with her in criticizing Op, and later the woman found out that he's a gamer as well, it tells so much about the kind of behavior backing the husband. However, they're supposed to fix the problem together instead of allowing the separation to occur. Gambling isn't fine to everyone's hearing, but the player shouldn't have kept it a secret, that said, the next thing to do is fine a way to convince the spouse to forgive his mistakes and come back to the relationship.
We don't know what kind of a woman she is and her view on gambling, which may have made her husband pretentiously joining her to condemn OP for gambling. Perhaps, just to make her not suspect he was also gambling if he had supported op. But issues of this manner isn't supposed to lead to separation of spouses if really they were having a very cordial relationship before she got to know about her man's involvement in gambling.