I don't think the four months apart was long enough, especially when you see him everyday at work and you both purposely ignore each other. That resentment and hurt doesn't just go away and that's why it carried over into your second effort. And you even admitted yourself that you proceded to just rant and vent and rage on him and he just took it. What was that accomplishing and did it make you feel better? I'm not saying what he did was right but when you choose to try something again, it has to be done with a fresh look and a rediscovery of what you guys fell in love with in the first place. You guys never got that. You guys didn't have the fun, taking it slow, rediscovery that you guys had the first time and when all the hurt feelings there still it was doomed from the start.
It's another case that when things go bad, it will never be the same again. When you are apart you really need to be apart so that all that residual hurt can fade away and you can be on your own and find that happy person you were before the relationship drained you.And it takes time. Only then can you possibly make something work with him again. Most of the time, it's much easier to find somebody else that you don't have the history with because then it will truly be a fresh start. I don't know what to tell you but as of now, there is no future with you guys. You are going to have to accept it and take it as a lesson about relationships and how rushing back into something when it's this fragile is never a good thing.
The first thing you can do is to forgive yourself for what you have done. I know you are beating yourself up constantly for the emotional abuse you have bestowed upon him for these last few months while he took it. You were hurt, you were emotional, and what he did has left a mark on you and your relationship. You weren't okay, you didn't know better. I know it might not seem possible right now but you can also try to forgive him for what he did too. He got very comfortable with the intensity and the arrangement you guys had and didn't think anything would shake your relationship, but it was wrong. He seemed sincere at first when he said he was willing to do whatever to make it up to you, but I'm sure by the third or fourth time you let him have it, he began tuning it out. Not to mention having you after everything he did was not exactly a consequence, although the beatdown you put on him was pretty bad. Forgiving him doesn't mean you have to get back together, but it will help you let out some of that anger and frustration and make you a better person for it. Those kind of feelings will just weigh you down and keep you drained for alot longer than you need to.
Waking up next to a beautiful girl,
Step outside and say hello to my beautiful world.