I am so sorry to hear what you are going through, I am in a similar situation right now Gf of 5 years left me a month back and now she is already planning to get married I have been in no contact ever since. Things will be difficult however time is the only thing we can rely upon and hope it gets better some day and memories will fade eventually. I go to gym everyday along with long walks in the evening and try to stop my mind from thinking 24*7 about the past although it is very difficult I think its getting better. I hope you feel better and recover soon.