I know that it's hard but you've got your whole life ahead of you, and the chances are if you got together then you wouldn't be looking for the same things in life. Although it's hard and it understandably hurts, he has moved on and so should you. If he's cheated on you then there is no way that you could fully trust him again, and truly believe that he wouldn't do it to you again. It sounds to me as though you have had a lucky escape. Just think of it as his loss, and eventually once he has stopped playing the field he will realise how much he has lost in cheating on you, and you never know, he may come back in the future!

A year may seem like a long time, but to be honest it's nothing. You have been split from him for 7 months, and it seems to me as though you are obssessed by him. He has clearly had a large impact on your life, and although you long to be with him it's not going to work out, his infidelity has proved this. It's time for you to wake up, move on and find someone else.