Need input ladies have you ever been here before?

Tomorrow is my fiances mothers wedding party and he came to me last night and said "guess who's going to my moms event and bringing her boyfriend " I was thinking maybe his sister or something and he goes No..

It was this woman that he had told me when we were dating that he was once interested in.. his mother runs a daycare when I lived there I always had to endure seeing her ..I am the complete opposite of her ..completely

When I heard she was going to be there I couldn't help but feel betrayed by my future mother in law because she knew how I felt about her since I told her while I was living in her home why I felt this way towards her

I am not looking forward to tomorrow

My fiancé continues to tell me I have no interest in her blah blah He's like you're my everything ..we have a child together ..

But it's the attraction he once had for her that gets to me am I wrong for feeling this way?

Please ladies anyone give me some insight/perspective 😶