I can't stop thinking about my ex. I really need help , I've seen a psychologist but it's not really helping?

Hello , like the title says , I've been through a break up with my ex-girlfriend. The problem is , it's been almost 2 months now but I still feel as bad as when it happened. I can't stop thinking about her and looking at pictures of her just keeps on making me cry about how much I love her. Every night , I can hardly sleep because I know I'm going to dream about her. It's killing me inside and I don't know what to do. I've seen a psychologist but it hasn't done anything great so far. My ex told me she doesn't love me anymore but I'm okay with that. I just can't get her out of my mind. I haven't seen her since the break up. She's supposed to come at my mom's wedding party in 2 weeks but I really have no clue on how I'm going to react , nor know how she is going to react. I've lost over 10 pounds from training since she broke up with me and I know I've mentally changed. I just need to know what to do because I don't think I'm going to be able to last long like this. If anyone has a hard time understanding what I mean I can clarify somethings out , so all you need to do is ask. Thank you to anyone who can help in advance. My relationship with my ex isn't horrible. When we broke up we weren't mad at each other nor became mad from the break up. She wanted to stay friends ans she actually insisted too. I'm also re-writing this question because I forgot a couple points , I almost didn't ask my ex to come to the wedding because I didn't want her to say no , but she actually said yes the second I asked her and didn't even need to convince her , making it way easier. But thing is , I don't know if there is a reason why she accepted so easily , even tho she says she doesn't love me anymore and wants to stay friends. She's not the type of person to do so. I can't wait to see her at the wedding , but I don't know how I'm going to react and more specifically , how I should react. Sure , I'd like things to come back to normal , but I don't want to do any bad moves.. What should I really do? I'm so confused right now.. I'm not satisfied with what I'm getting as responses but I clearly know that it isn't easy to help someone you don't know. I've been told that using reverse psychology helps and waiting and sending her a hand written letter. I don't even know what to do as I've tried pretty much everything I could. I don't even know what to write in said letter. I've been struck by illness since I broke up with her but I don't want to link it with it even though I know it probably is. I can't find a way out of this and It's killing me. I've been pushed by my friends to call suicide hot-line because they were scared of me trying to do something stupid. My ex isn't doing well either. She's down most of the time and she's been sick for 2 weeks straight , but she has no clue I'm living this. She probably thinks I'm going through this like a pro but I don't want to tell her anything , because I don't want to lose her as a friend. It's my 3rd attempt at trying to get a good idea on what to do but I'm still clueless , someone give me tips or something , I need help! :(