Iriacynthe,
I had the same thing happen to me about 5 years ago. Granted the downward spiral started a lot earlier and I only invested 8 months of my time but he had already asked me to marry him and we already had our children named. I know that seems kind of fast but I've only had 4 serious relationships. I never date. I can tell right away if I have an attraction and if I see potential. Usually all my relationships move really fast and are really intense. I like it that way... lots of passion!
My ex was extremely insecure and would always tell me that I was too good for him. Eventually he pushed me away enough that I was forced to dump him. One month later he was with some other bitch. Later I found out that she was nothing compared to me. Not that I'm all that and a bag of chips, but I was definitely better than that girl for him. He just felt more comfortable with her because he felt he could hold on to her. He was always sure I'd leave him.
I know this may not be exactly what happened with you and yours but the insecurity thing and the speedy replacement are right on.
Please don't lose faith in love. Love is the strongest source of joy. Only in love can you experience such pure and unadulturated joy. However, it is a double-edged sword. The amount of joy it can cause is exaclty proportionate to the amount of pain it can cause. That's what makes it sooo wonderful. That element of bitter sweetness. It also makes you enjoy the joyful moments that much more. I couldn't and shouldn't be any other way in my opinoin. Embrace love and all that it is. Joy and pain. Escape is futile!
Really though hun, it is always worth experiencing and it is when we grow the most as human beings. You'll let go in time and find joy in someone else who finds that same joy in you. I promise you that doll.
*tight hugs*