Given the fact that this person was your closest and dearest, try to do everything possible to breakup was painless. Talk to him, Express everything that is troubling you, and - most importantly convey - to your ex boyfriend (girlfriend, friend, PAL, loved one), why you want to stop your communication. Do this delicately as possible, without hurting the esteem of your interlocutor. Remember that everything in life is cyclical: if you cause someone pain, it will come back to haunt you.
The person that you want to stop to chat, must be aware of the fact that you each other do not come. Depending on the reasons for the separation, depends on the entire process of rupture. If your friend or loved one you just got tired, became uninteresting, attach a maximum effort not to make him a notorious personality. Reduce communication to a minimum, but not sharply, and gradually. If this person has caused you serious harm or brings a solid film, of course, such a person must break off the relationship abruptly and with no chance for rehabilitation.
There is also the option, when you seem to have decided to end the relationship, but still remain some doubts that hinder to do it. Then you just need to calm down and just talk with that person about the fact that you are not happy in your relationship. Express all that pent convey to the interlocutor the cause of their grief and resentment. Perhaps, then, he realizes his mistakes and sincerely ask forgiveness.
After that, you should think about life with the saying that real friends are easy to lose but hard to find. Remember that every time you decide to breakup, always pre-weigh all "for" and "against" and never do it spur of the moment.