This wasn't a case of him bailing when the going got tough....this relationship sounds horrible and I'm thinking he was right to walk away. Him previously cheating, you now moody, shouting and taking out your general unhappiness on him - why would he risk returning to this mess?
The two of you are very young. Most of us have numerous relationships before we find "the one" and I'm sure you'll be no different. Chalk this one up as a learning experience
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.