Missing my ex!

I was with my ex for 2 and a half years but left him for my boyfriend now.. Because he was a little controlling but he wouldn't give up on me for a long time and when he finally did I started to miss him, his moved on now but he occasionally messages me saying he still thinks of me... He was like my first real love and it just breaks my heart how stupid I was listening to other people... He done so much for me and I knew I could trust him! Though the guy I'm with now has hurt me already so much... :( 
I want to leave him because of it but I'm so affraid of being alone.