I'm not sure if I love my ex or if I just don't want to see him with somebody else?

I had a boyfriend and at the beginning of the relationship i couldnt have been happier with how it was going, we were getting on so well, my family and friends loved him, i got on with his family also so it was all going really great. Then a couple of months into the reltionship we started to argue a lot, almost every day over the simplest things, it started when we went to a party and his ex was there and she warned me of him, just saying that i should be careful, and i know she wasnt doing it to be selfish as they are still friends and she is in a happy relationship with my ex's friend. Nobody would ever tell me why they broke up other than she cheated on him, but why would she of warned me of him? Then i started going to a couple of parties without him and he became very possessive, ringing me up every half hour, asking exactly what boys were at the party etc. I started to lose feelings for him and my friends suggested i should tell him, i confronted him a couple of days before i was going on a 2 week holiday and he went mad as he is quite an aggressive person. Then the day before i went away he came round and it was very awkward, i could hardly look him in the eye and we had a big arguement. He told me he wanted me to go on holiday and have a think. When i came back i phoned him straight away and told him i wanted to be single cause i didnt know how i felt and didnt want him to be tied to me if im not sure how i feel. He kept accusing me of cheating and keeps saying how he has his suspicions just because i dont feel the same, this really upset me because i would never cheat. However, he still keeps telling me he loves me and in his words "he is still defensive of me and if he saw me with another lad he would go for him". And he keeps guilt tripping me into getting back with him telling me and everyone that he loves me. Im trying not to fall for it but this is where im confused, i think about him every day i cant get him out of my head. I keep telling myself and my friends that im not going back to him and that we are better as friends, but i miss him and i wouldnt be able to see him with somebody else it would really really upset me. I really dont know what to do because i dont want to get back with him but dont know if this is normal to feel like this after a relationship has ended or if i love him?