He says he can change

Jayne asks :

I have been in a relationship for 6 years, 2 years ago he go a new job working away, at the time I didn't realise how troubled he was, I had started my own business, and was very busy myself. He went to work in the Indian Ocean on oil tankers as security, the first trip he took, we were texting and emailing to make sure he got there ok, and it was ok, then all communication went quite, for days, I got really worried thinking he'd been captured by pirates! So I checked his emails and on there were email from another woman he had been having an affairs, I ended our relationship at that point it was 4 years, he the. Begged and begged to come back and we went to counselling, it was really difficult time and I got very depressed over the whole situation, 2 years later, we were still on, but it got to a point where I needed to know what was going on with out relationship. My parents go involved as I was very upset, and asked him do you intend to marry her, and he couldn't say the words, so I said you either marry me or we end it now. As marriage is what I want. So we got engaged, 2 months ago he left me, didn't tell anyone he had broken up with me, he saw his friend in this time and didn't say a word to then, then he went back to work abroad, he goes away every few weeks for weeks at a time, i then had to go to a friends wedding and announce to all of our friends that he had left me. Very very hard, in the time he was away the only contact I had from hid, was to say that he had cancelled our wedding venue. I was devastated. I went to a friends 30th bday weekend away and meet someone, we started seeing each other. My partner then came back, we discussed selling the house and he was painting it ready for the market, he found my phone and read all of my messages while I was out, calling me in tears and asking if I had a new boyfriend. He then of his own occurred has started to see a therapist. I have since stopped seeing the other guys and my partner or ex partner has said that he wants me back! I have no idea what to do, I don't want to have regrets, I don't want to regret not getting back with him or regret getting back with him, I have always believed in the fairy tale romance and wedding mean a lot to me, he has broken my heart and he know this, but he says he can change and become the man I want. But I have heard all this before from our first break up and then look what he did. I'm at a cross roads and I really don't know what to do!