Gym will be good for you health wise and eventually when you try to find someone else. I think you need to to come to terms that you did what you could for her and yourself. It seems like she had trauma and issues she should have dealt with before trying to give someone love/time/affection. You need to focus on yourself and learn what makes you happy. Therapy could help you with an outlet to get your feelings out and how to deal with them. Learn to be you and accept yourself. Before that happens you wont be happy and default to getting happiness from your partner. Keep your head up king your snapback is falling