How do I fall out of love without hating

So, a few months ago my relationship with a girl I was dating ended and I can't seem to get over them feelings I have for her without replacing them with hate. She was the first girl I fully trusted and opened upto and she just wanted to date me for fun I guess. I feel hurt and used but she also complimented my personality the best out of all the girls I have dated. I already had trust issues but now I can't help but question if girls just tell me what they think I want to hear because that is how she made me feel. More recently I have gone through a lot of death in my life and I can't help but think about how supportive she wpuld have been. It's like I can't stop thinking about her. I either have strong negative feelings due to feeling used or strong feelings towards her because she was the last time I truly felt happy. I don't know what to do. I have so many conflicting feelings about her.