You've already been advised to move on with your new life without your ex-boyfriend and that is exactly what you need to do, because you drove him away with your jealousy and you can't go back and change that.
That said, you must deal with your jealousy problem or you are just going to continue to destroy any further relationships that you have. This is NOT something you should just accept since excess jealousy is the sign of real serious problems.
Jealousy is not natural, but some cultures accept it as being so - this is absolutely untrue and it is the root of lots of trouble. Here in Brazil jealousy is considered natural and it is shocking how many people are murdered every year by jealous partners, ex-husbands, ex-boyfriends, ex-wives as a result of people simply accepting it as normal and doing nothing about it.
Jealousy has its roots in you, your past, your own emotional make-up and it won't just go away, you have to get counselling. Your message is quite clear that you are a very needy person emotionally. Your jealousy stems from a lack of self-image and a lack of trust in your partner. You have to learn to look at yourself differently and to come to understand that YOU are worthy of being loved. You also need to learn how to trust your partner and not suffocate him with your jealousy, watching every move constantly, demanding to know where he is every moment, what he's doing and who he's with. This is, no doubt, exactly what drove the other boyfriend away - it's a form of control. You can't control anybody but yourself and that's what you need to learn most of all. If you pick somebody who will cheat on you, they're going to do it whether or not you're hovering over them 24/7 or not. In fact, they're more likely to cheat on you because the hovering becomes an annoyance that destroys their feelings for you.
Learn to pick better partners, learn to let them have their own space and not invade it. Trust them until you have some reason not to and don't go inventing reasons. Make the pain you're going through right now a learning experience. You need to learn how not to force yourself to go through this pain again and that can only be done by changing yourself.
Good luck to you, God bless you and give you strength to do the really deep soul searching that you must do in order to correct your problems.
Jealousy is NOT love, it is not a sign of love - trust is a sign of love and respect is a sign of love. If you have those two things and you give them to your partner without hesitation you won't need jealousy.