I recently found out (from my fiance) that he and a really close friend of mine were interested in dating each other, flirted and kissed a few times while we were broken up for a few months. I left the country because I couldn’t deal with being in the same city as my ex, who was treating me like dirt due to his own feelings of anger and rejection.
Someone intimated me of the fact that he and this friend of mine were together, while we were broken up (and I had always had an insecurity about this friend of mine and my then-boyfriend even when we were together).
Confusing, I know, but let me try and get it out before I lose my mind.

I sent her a text message (I was in the US, my ex and best friend were in Canada) expressing how hurt I felt. I thought they had cheated on me. A week later my ex was at my doorstep trying to clear “their” names and clearing his conscience in the process. He told me multiple times that they never dated and there was nothing between them. What he deliberately didn’t tell me was that they were very much interested in each other but because the friend’s parents didn’t want them to be together and because he apparently realized they weren’t meant for each other, the relationship didn’t materialize. He called her in front of me, put her on the speaker phone and she confirmed that there was nothing going on between them.

When he saw me however, old feelings came back and we decided that we wanted to get back together and be serious about each other. However, he said he couldn’t tell any of his friends, including this mutual friend of ours, because I had ruined things for him and her with this false accusation. That everyone had found out about me sending her this message with blatant rumours. I felt terribly guilty and so I agreed to keep our relationship a secret till he could slowly and systematically break it to everyone. So he told everyone we were civil and kind of acquaintances who may think about dating in the future if we are in the same city. On one of my visits to him, I met that girl and profusely apologized for falsely accusing her and ruining a healthy friendship between them. I humiliated myself and apologized to all the other people affected by this as well, who all probably thought I was a jealous spiteful ex.

When my fiance and I decided 10 months ago to get back together, we made some ground rules about his anger and my insecurities (from a previous ex cheating on me). This time, we involved our families. I quit my job, and moved back so we could be together. Even took a dip in my budding career to prioritize my relationship.

Apparently, my friend has been feeling guilty that they were deliberately lying to me about their involvement and wanted to come forward with the piece of information. So my fiance decided that it best come from him than her. He point blank tells me that it’s none of my business what he did in his past while I was not in the picture but he wants me to know because apparently this friend (who now knows that we are recently engaged) can’t be happy for me and the only reason he is telling me is because now it directly affects me.
With the friend disrespecting me and potentially hurting our future, he is telling me this piece of information which ideally is irrelevant to me (according to him). With great difficulty, I see some twisted reason there. Fine. I give it to him.

The friend still has feelings for him (unconfirmed assumption) which is why he didn’t tell her and the rest of the friend circle. He wanted her to heal and get over it and still be friends with him. What I absolutely cannot get over is the fact that he kept our EXTREMELY serious relationship a secret and let me think that I was the reason for it. I confronted him and we have been fighting for days now. I asked him to clear all the confusion and tell everyone that we’ve been together for 9-10 months and this engagement is not a brand-new thing just because I moved back to the city. He sought me out, he came to see me, I moved here for him/us. He repeatedly tells me I’m not entitled to any of this information and that his friends don’t care what I texted or said in the past. The point is to move forward and let them know that we are NOW engaged and getting married.
It kills me to think that all these months I’ve been feeling guilty and sad for breaking his friendship and jeopardizing his relationship. He refuses to set the record straight and our fights have become unbearably ugly. I’m marrying him in less than 100 days and we are very unsure if this marriage is going to work. I feel disrespected, hurt and uncared for. His friendships took precedence over my pride. He doesn’t trust me when I say anything to him, says it’s my ego and past baggage/insecurity talking when I ask him to tell everyone that we’ve been together (albeit long distance) this whole time and that my accusations weren’t fabricated.

If you have managed to read this uptil now, please guide me.