I know feeling like someone was moving on faster than me felt yucky. It was easier (and probably more realistic for me) when I realized that what I view as moving on is probably a version of stuffing feelings etc. I have done that before, and know that I have grown enough that regardless of how much it hurts...stuffing only makes it hurt worse, and come out ten times bigger down the road.
I think you should feel good that you are feeling this hard stuff now.