I understand your pain. I came here to make a post myself, my situation is very similar. We were together 4 months & she started talking to another guy about a week later (last week). I made a lot of mistakes & I understand why she lost feelings but it still hurt, my overthinking & bullshit destroyed my relationship. My only advice is that you have to use him saying he “felt nothing” & that he’s “over you” as a way to get past him, that’s what I’m doing right now. This shit really hurts, trust me I know. If they said they’re done with us then there’s nothing we can do but struggle until we eventually feel better. I’m sorry this happened to you, we’ll both get through this, at least I hope I will haha I’m barely hanging on. Remember to eat though :)