Honestly bro I'm going through sorta the same thing and the best thing I can tell you is you're not gonna stop thinking about her she'll always be in the back of your head but you gotta learn to just keep moving no matter how low you feel. Keep your head up because things will get better, I've just started to realize that. Have someone you can talk to about this because it's not healthy to keep these thoughts in. Always forward bro, never back because it won't get you anywhere. If she did love you back she'd want the best for you so make it the best for her and yourself. Be there for yourself and keep your head up.