I would advise taking a step back and thinking about the reasons why you want to keep this relationship going when you aren't feeling good in it. At the end of the day, if you're feeling insecure after reconnecting then it's because you're not feeling good where you are right now. Sometimes the thing to do is to let go of the things that are adding to your low vibration, which in this case, could be the relationship. A relationship isn't just the creation of one person, but of both people together. You can't just force yourself to be happy and secure when you're not and you can't force him to want to stay. The best thing to do is to really check in with yourself and say 'ok, what do I REALLY want in life'. Surely what you really want is to feel good the big majority of the time and be with someone who wants to be with you and supports you and you support them. I would take this as a sign that you need to step away from the fire before you get all burned up in it and take some time to really build yourself up and find out what you want. 
I think you need to start looking at this from another angle, from outside of the relationship and think 'do I want to be with someone who genuinely feels we have no future? Do I want to feel that insecurity and that sadness all the time when I'm around him that I'm somehow not good enough for him? Is that what I want?' Because someone who has a really good idea of what they want would step back and say that no, they don't want to put themselves through that. That they want and deserve more. 
There is a possibility of everything in the universe happening, but that isn't going to help you out now. The only thing to do is to take this man at his word right now and distance yourself from the negativity and build yourself up. 
Abraham talks about how we teach others how to treat us and that is very true. You can vibrate positivity and joy and happiness all day long but he will step all over you like a doormat if you don't give yourself self respect and value. The only thing to really do in this case right now, is to walk, otherwise, he will just walk all over you and create more insecurity in your head and you will be driven insane. Then let him come back in his time when he realises what you're worth. 

Thank you so much for your reply! I would love to say that this is the only difficult thing in my life right now but it isn't. I am someone who suffers from anxiety and depression and in ALL areas of my life I seem to be struggling. When I attracted him back we were great, as I began to fall back into old patterns, our old problems showed up. It is really upsetting because we love each other very much and he says it and I know we are meant to be together. Could it be his past relationships? We are also long distance as we are both in school. I don't want it to seem like I'm making excuses but I let go once before and he came back and the relationship was great. What I truly struggle with is falling back into my old patterns. As you previously mentioned, I definitely would want to be with someone who lifts me up most of the time and he did that up until I felt a shift in my vibration. I will take your advice and step back and do my own thing for now and see what happens. Thank you again 

I guess it is really hard to deal with my depression lately and I totally let it overcome my life even outside of my relationship. We left each other on good terms  and even kissed and said "I love you" when he left for school. I know he is the right person but at the same time if I am not 100% myself and vibrating high so there is no way that we could ever be in a successful relationship. I am going to take your advice and work on myself by myself for now and see what happens-which I already know is us being together. Thank you so much!