If you decide to use a break up letter to end the relationship, you need to go about it carefully. You don't want your words to be misconstrued. In fact, you want the letter to result in a clean break. You don't want a relationship that is like a hangnail: sort of over but not really. If you write a break up letter, you need to be clear about what you want.
When asking for help and advice about how to go about this break up letter, know that you should make the letter personal but not too personal. Do not type the letter. Instead, handwrite the letter so that you show that it took you some time and that you didn't just type it up on the computer. Keep the look of the letter simple but sleek. Use thick paper but don't go all out and invest in fancy stationary.
Plan what you want to say before you write the final break up letter. You want to be sure this is the letter you want to send before you mail it or slip it beneath his or her door. Be clear but don't place blame on either of you. Instead, explain that some relationships do not work out. Breakups hurt, and you don't want to make things worse.
The most basic breakup advice you can receive is to be clear about what you want. Do not leave things open if you do not plan on ever getting back together with this person. Don't ask for a break if you really just want to stop seeing this person. If you want to be friends with this person, explain this but also explain that it will take times. You can't go from sleeping in the same bed to seeing films together in a platonic sense.
Avoid the word love when you're writing a break up letter. You don't want to patronize talk down to the person nor do you want to give them false hope. The best bet is to end the letter with your name.