If you talk to anyone who, like you, has been through the pain and anger of a break up, they will more than likely tell you to just leave your ex alone for a while.
You will also probably hear from them how they cried, begged and pleaded for their ex's to come back to them, only to have their ex's resent them even more.
The advice from these people to leave your ex alone for a while is excellent, and will help tremendously in getting your ex back.
You will be very wise to accept and carry out this advice.
There are two reasons why you should not contact your ex directly after the break up and be overly emotional about the relationship failing.
First of all, your ex is still very hurt and angry about what caused the break-up and needs to get over all these bad feelings.
Secondly, every time you contact your ex and cry and beg him/her to come back to you, he/she will think that you are trying to make him/her feel guilty about breaking-up with you.
You will not succeed in getting your ex back this way, because you were both probably to blame for the break up, and it would be unfair to make your ex feel that he/she is guilty for the relationship failing.
If you want your ex to regret breaking up with you, you have to give him/her the feeling that he/she did the wrong thing by breaking up with you, and want you back in his/her life again.
This is only possible by showing your ex that you are a confident, strong, positive person, very able to handle a crises as well as very willing to sort out any problems that you and he/she might have.
This will be a much easier way of getting your ex back than offering him/her a negative person who is given to emotional outbursts at the first sign of problems.