I had that problem. Then we split up and im still not over it even now, but it is a hell of a lot easier now than then. Like the song Hearts dont break even.
You have a few options.
1. Hes probably not that into you anymore. So look on the net for pictures and vid's on music channels and Youtube and study how other girls that you and others think are sexy and copy that they do with their hands, eyes etc. Don't worry about that shit about being my own woman etc it just don't cut it. Men are inherently shallow when it comes to looks and sexyness, not all are but they are built for finding the best looking mate and making baby's and moving on. Not their fault its just genetic. This gives you the power though so don't forget that.
2. He's probably a dick head and cheating. So your gonna still miss him but dump him any way
3. Even if hes cheating or not say we need to talk or have a break and resist texting or talking to him unless he texts you and then give him a one word text like "k" or somthing. Make him chase you for a bit and then say you want to go out for dinner and make him treat you. If he don't just disappear again for a bit and go out with your mates and flirt with other guys. If this don't work and he just don't bother then you will have to take it on the chin and walk away.
If you walk away then remember back to before him and think "Ok. Before I met him I was out and about and then I met him and that was easy and we had a relationship. Now hes gone someone else will come along in the same way or even a better way, like a high flyer at a casino or somthing and a will be all loved up and swoon and think to myself, why the hell did I bother with that guy that just wasn't interested in me".
Its hard but fill you time with stuff and go out, cry a little and then go make some food go to bed and keep doing this until it don't hurt as much anymore. It really is bizzar but time does heal it and make it better as if its healing a cut.