Stuck in Love

My Ex and I broke up over 3 weeks ago and we had been going out for 6 months. At the start of our relationship everything was perfect, it took sometime but I fell in love with him whole heartedly. Through out relationship we had some great time and we had some pretty shit ones too, 3 months in I got pregnant while on the pill and had an abortion because he felt like we couldn't give our child the best start in life as we are 17 & 18. He was a know it all and I could look past it because he made me happy, sometimes we'd fight over it but we were so perfect for each other. I had guys messaging me constantly on social media and I wouldn't reply to them and sometimes would block the ones that persisted. Towards the end of our relationship I started to feel like I wasn't in love anymore and went to a cattle show and met a guy that I'd been friends with for the past three years and while I was there I forgot all about him and kissed this other guy but felt guilty afterwards and regretted it immediately. Anyway my Ex broke up with me because he felt like I didn't appreciate him enough when I would've given anything and everything to him if he asked, even when he wanted to fuck 4 times a day. I've seen him 3 times since we've broken up, the 1st was at a party, the 2nd he asked to talk and come see me and I gave him some stuff he left at my house and the 3rd was last night when I told him I wanted to talk and as soon as I got there he started to get all frisky and we fucked twice. When we are together last night he had mood swings, like we'll be getting along great and laughing then he would get all serious and get shitty. He says he doesn't see us being together again for a while like in 8+ years but I want him now, I feel like I can't live without him and want him in my life, I will literally do anything to keep him in my life. I feel like he does want me back from how he acts around me, I have no clue what to do, I really need some advice? Sorry for the long post!!