bad case of lust, advice please

Okey so for starters I am very reserved with my body , i just don't let a man touch me just like that, i also don't have sex , but do other stuff (I'm very creative).  I broke up with my ex 2 years ago and he has been the ONLY one I had let touch me and the only one that has seen every inch of my body, he knows what I like , he does everything just right and how I like it . I couple of months ago we ran into each other at a bar and we ended up in his house. I loved it and I felt so much emotion that at that point was not clear but now I know what I felt and it's lust. Iam relieved at this discovery because I thought I was in love with him or soemthing but it's just really really strong lust. Right now I'm in an open relationship with this guy I known for 3 years but it's not the same, like we start making out and that's fine but when things hit up I just loose the mood , and i try so hard but I just don't feel it, I also tried another guy to see if it was a chemistry problem but no,all i desire is my ex and it's annoying. Any advise? Sorry for making it long.