U can't forget a person otherwise moving on would be easy for all of us. Just accept the situation for what it is and start focusing on bettering urself. its all about time and what u do with it. If u keep hanging on u will never move on, if u focus on other things these feelings will subdide or become bearable as each day passes.
First you let yourself feel those feelings. Like you're grieving the loss of a future, s relationship. It will hurt but don't deny yourself the opportunity to experience that.
It just happens over time, just wait and try to focus on other things. I can tell you one thing, it happens faster and faster every time.
Yeah this is a pretty great question because I'm in that situation or have been for the last couple of days and all I can say is just be close friends and don't do anything that will make you show your feelings at all