My [26M] father [50sM] just announced that he is going to marry my fiancee of four years' [28F] mother [50sF]

((Throwaway because the fam reddits))

The title.............pretty much says it all. Last night, I took my fiancee out to dinner with my entire extended family. I was planning on announcing our wedding plans (and asking my brother to be my best man) at the end of the event. However......

At the start of the dinner, before we had even been brought our foods, my father stood up and asked for everyone's attention. He said that he had met a wonderful new woman, that she had taught him to see the sunshine again, that he had never been happier. We were all overjoyed- my father has been deeply depressed since my mother died of cancer eight years ago, and we couldn't believe that he was happy again.

And then my fiancee's mother walked in.

My father said, "This is [fiancee's mother]. I am so happy to introduce you all to her, although, of course, you may already know her daughter, [tthrowaway27's fiancee]. I am so happy to introduce her as my future stepdaughter, and I hope to see all of you at our wedding this November!"

My fiancee and I were SHOCKED. We had no idea that our parents were dating at all, and it made the rest of the dinner uncomfortable for us because, a), we could no longer announce our own wedding, and b), people kept clapping her on the back and telling her what a phenomenal older sister she would be. Which, gross.

What hurts most about this whole thing is that I have been VERY open with my father about my wedding plans and how much I love my fiancee, and I even told him that I was going to announce that we were going to get married last night. He knows that I have been keeping it a secret from the rest of the family due to various past relationships (and some superstition), and it feels like he purposefully announced his engagement to my fiancee's mother so that I couldn't marry my own fiancee. He even scheduled his '''wedding''' before my own.

I am incredibly happy that he's happy again, and I do believe that that was sincere. I believe that he loves this woman. But I cannot believe that he has done this!

tl;dr My father announced his engagement to my fiancee's mother the same night that I told him that I was planning on announcing my own engagement to my fiancee. Wtf do I do???

EDIT: to answer some of the questions in the comments, no, my father has no history of acting like this. He's very shy and conflict avoidant, but he has been incredibly approving of my relationship with my fiancee, 100% supportive. My fiancee's mother has no contact with one of her children, but she has also been super supportive of our relationship.

Also, this dinner wasn't an engagement party, but a family reunion. My family is rarely gathered around, so that's why I was going to announce it there. My brother and my sister both knew about me dating my fiancee, but not our engagement. They were both absent from this dinner (surgery & children, respectively), and I'm not sure if they've heard the announcement from my dad yet. I haven't gotten any contact from either of them yet.

Submitted July 30, 2018 at 06:25PM by tthrowawayy27 https://ift.tt/2LFjIBG