Dear Inailz, it is very hard. It's even more incredibly difficult to move one without any explanations or reasoning of any sort. Somehow though, we simply have to learn that some people are not worth it. They are not worth constantly doubting yourself, feeling insecure and spending your moments with them wondering about who they're thinking about.
It is like Sarah Starfish said -it is highly important that you raise your standards now. Look for someone who can help you feel more confident about yourself, by showing devotion, love, and most importantly, an openness and honesty in which you deserve.
I feel for you Inailz, but you will be able to be stronger from this and in moving on. You are obviously better than this man, and deserve a much much more secure relationship. This isn't to say you need be more paranoid, only in that from this you should walk away from these feelings from him in having learnt a lesson. That being you deserve the truth in all situations of any relationship, you deserve a loving man, one who appreciates all you have and you for you.
He, as demonstrated by his cheating, cowardly behaviour, that you spoke of, was never going to make you happy and least of all content. And in an ideal relationship, that is what you should be looking for...
I hope you realise that you are not only strong, but will oneday feel this strength, in having ended these two damaging and wearing relationships with your dignity about you.
I hope you find someone that will forever love you