Is it normal to have feelings of jealousy towards your "first love"'s relationship, years after you've broken up?

Me and my first true love parted ways over 3 years ago. I’m now in a more fulfilling relationship with a woman who is much more compatible to me, but when I see my ex talking to her new lover on facebook or saying the things to her that she used to say to me, I get this horrible feeling in the pit of my stomach that I can only describe as deep-seeded jealousy.

I wouldn’t get back with my ex, even if the opportunity came up to do so. Although there are many reasons why I wouldn’t get back with her, the most important reason is because she came home from work one day and moved out, with no warning or explanation. I called her while she was on her way home to tell her that I had picked up the mail and had dinner made, and she responded as if everything was okay, but when she arrived home her dad walked in after her, and they packed her shit and left, leaving me in a state that I had moved to soley to be with her – I had to make the 4 hour trip back to my home town in the middle of the night, in shock of what had just happened.

I don’t know if it’s normal for me to feel this way. Have you ever gone through anything like this before? Is this normal, or maybe I am only feeling this way because of the circumstances surrounding the ending of our relationship?