How do i put my boyfriends thots behind me since he broke up with me

After 3 and a half years with my boyfriend, he broke things off on September 30th. He said he was no longer happy and wanted to be single again. I've been begging him for the past two months for another chance but he's adamant. Now, I've been having these suicidal thoughts. Sometimes when I'm sleeping, my heart just stops and I literally can't breath for close to 5 seconds. I don't function normally anymore. My friends keep telling me I will heal with time but the way I'm feeling, I feel like I will one day just drop dead. I have headache 24/7 just from thinking about him. I've tried, I've even gone to church, I can't stop hurting or stop thinking about him. Just this weekend I thought dying would be the best way out but I don't want to die but how do I stop my heart from hurting so much ...#LindaIkeji