If you intend to rekindle your relationship with a jealous ex boyfriend there may be certain changes that need to be made first, which will help you to have a happier experience the second time around. In order to make it work you will need to consider what it was that led you to abandon the relationship previously. Is it something that has altered? Or is the behaviour that you couldn't cope with likely to resurface?
Jealousy can show itself in several different forms, from verbal abuse to physical violence. Some jealous boyfriends can be hot headed, and so are prone to combining their heated emotions with physical acts. Such behaviour shouldn't be acceptable in any boyfriend, however dear to you they are.
If this scenario sounds familiar to you then perhaps you need your ex boyfriend to prove that he has made an effort to change since he last dated you by attending anger management classes to help him control his emotions.
Other forms of jealousy don't result in violence but can still be pretty unpleasant to have to deal with. Constant accusations that you have been seeing someone else, or arguments about how you should dress in public are all signs that your boyfriend is suffering from insecurity and needs to let you be your own person, instead of attempting to keep you under his thumb.
If these were the types of experiences that you used to have with your ex boyfriend then ask yourself whether he has changed his ways. Altering this type of behaviour doesn't happen overnight. Usually it involves the perpetrator attending counselling sessions to learn where his constant control issues and lack of self belief stem from.
If your ex really cares for you is he prepared to prove to you that he is actually doing something positive like this in order to establish a better relationship with you? Or is he merely verbalising that he is different now? If he is telling you that he has changed, however wonderfully he puts this to you, the chances are that he would like to get you back and so is saying exactly what he thinks it will take in order for this to happen.
It may be that your ex boyfriend is willing to attend couples counseling with you. If so, this could be a great leap forward as it shows that he is committed to you and really does want to change. By going with him to seek help you may learn more about him and why is has behaved as he has in the past, plus instigate positive change and work with him to make it happen.
Jealousy is a negative emotion most of the time, especially when taken to the extreme, and if you really want to make it work with your jealous ex boyfriend then he needs to be willing to change his jealous ways.