Its as simple as this;
Dear ____ ,

Maybe this was a bad idea. This isnt working. You sed you was going to be careful about it but your not. You dont watch out for the words you say, the things you do.  You use certain ways to hurt me. I dont get it. I keep thinking your wanting something more than what I can give. Its like Im not enough. You say Im all you need but I don believe that. You can say it, but you sure dont show it. You dont need me. You think you do cus I actually stick around for you. I actually care for you, and everything. I show you how I love you..maybe not enough? Idono. Maybe I made a mistake? I shouldnt have let this continue. Maybe I was supposed to let you go and move on. Its hard to decide. Help me. Give me a sign if going thru with you is the right thing to do.