Thank you for your question! Friendships are never easy, and they can be very strenuous in your life, but it is essential to end any toxic relationships you have. In high school, where people are trying to figure out who they are, it can sometimes bring out a different side of them you might not like. Relationships are going to be tricky and messy, but if you are to the point of no return, it makes no sense to keep putting energy into it. Even though it is sad because you have spent lots of time with this person, just keep in mind that this is for the betterment of both of you. I think one way that you could break up with your friend is to start to cut them out of your life. Keep in contact and say hi to them, but do not hang out with them as much. Start to sever any ties to the relationship that includes spending a lot of time together, which will automatically not make you as close of friends. Limiting that time also will help not make the relationship as stressful since you are not putting so much time into it. Having those baby steps in the right direction will, in the end, help break up your relationship. It is going to be a hard, and be a sad process, just make sure that you remember that in the long run, it is going to help both of you. People come in and out of our lives for different reasons, and sometimes the ending of those relationships comes sooner and harsher than others. Remember the good times and who knows, maybe you could come back together as friends later in life.