Dear Anonymous,
I can imagine the shock you felt to hear those words from a man you are about to get married to. It would hurt no matter the gender of the person he was talking to. Your fiancé telling his male friend that he "missed their intimate moments together" doesn't sound like he is "a changed man", as your mum would like to believe.
For the benefit of others reading, it is true that some boys in high school engage in some form of sexual activity with fellow boys, and it doesn't necessarily mean they are gay. Sometimes their hormones are raging and they'll stick their penises into anything. Some do grow up to realise they are gay, but many turn out to be homosexual men who once "experimented".
That said, your fiancé wouldn't be saying what he just said to his friend a month to his wedding if he weren't gay or bisexual.
I cannot tell you whether or not to call off your wedding because it is your decision, but I strongly advice you not to get into a marriage that you did not sign up for. When you agreed to be his wife, you did not know he was gay or bisexual. Even if you feel you can get past it, can he? Is he using you to hide his sexuality? Does he love you? Will he be satisfied sleeping with a woman for the rest of his life? Unless that is something you want to continue dealing with all your life, you're better off bidding this man goodbye. Don't let external pressure force you into a marriage you will endure alone.
Even though he didn't tell you and you found out in a shocking way, be the better person and talk to him before you call it off (if you decide not to marry him). Make up your mind and then let him know why you are calling off the wedding, and don't listen to any empty promises. Let him go his way.
Don't disgrace him publicly or maliciously spread the news that he is gay; it will do nothing for you. Only very close people deserve to know why you are not marrying him anymore. Let him come out of the closet if he chooses. That's not your problem. Focus on yourself, on healing and moving on. It won't be easy but you will be better for it. Your mum and others will be alright in the end.
I wish you the very best as you take on this ordeal. You will come out on top.
Best wishes,
Ms Sugar