Good tips above. Only thing I can say is "he's an Ex". You're talking like him a bit like he's your husband having an affair. You've got a broken heart but you have to live your life, not his. You've stayed single for this time for any reason? Was it in hopes to get back together with him? If so, that isn't happening (he has this girlfriend/fiance) - so the best thing for you is to just treat him as an Ex and start to build strength to push him away.

I have warm feelings about Ex's too. I know one of my ex's got married on my birthday - so that's not hard to forget. At this point in life, your relationship guidance lies within you. If you want someone in your life you have to attract that into your life - if you want to stew over this guy who is long-gone, then you will attract that into your life too. You make the world you want to live in - so buy the right ingredients to make a different receipe. If you want to worry about this guy, you will make that happen.