Thoughts, Decision, I Dont Know what To Do!!!

Last night I got told by a family memeber that my fiancee said, I went to the casino without her knowing, but i have not told her because i wasted most of the money from my paycheck, and they said are you telling her or ill tell her, and wellhe said he was going to tell me, so he told them few weeks ago and well i just found out last night. Should i tell him or what because i don't know what to do. My thoughts is why did he not tell me if everytime he asks i always tell him to go, just not to waste all the money because we do have bills to pay. My question here is im wondering wether he went alone or with someone. what do you think I should do.