Most Helpful Guy
You have said yourself that telling him will probably ruin your friendship. You have made the mistake of thinking that you can switch from being in love with someone to being friends without having to heal first. That almost never works out. You cannot avoid the pain process by lying to yourself about being able to stay friends. To get over someone you have to go through the grief process and you have just been putting that on hold. The result is that you are dying a slow death every day rather than moving on and healing properly.
What you should do, in my opinion, is to tell him that you still have feelings for him and that those feelings are why you must break away from him in order that you can get over him. Then you should cease contact and actually deal with what you have been avoiding. The sooner you face it the sooner you'll get past it.
Most Helpful Girl
You just sound like me. I was in depression, I had a boyfriend but I knew I had feelings for my ex who also was my friend. The moment I broke up with my boyfriend I felt so free. I felt liberty. I knew I loved the other boy. I regret the relationship I had with my then current boyfriend