The truth is no one knows tomorrow, the very next minute could be a turning point for you, and that turning point may or may not involve pain, regrets, and a whole lot of other emotions you probably wouldn't want to confront.
Know this and know peace, you will make the wrong decision a lot of times in your life, you will say wrongs things at the right time and right things at the wrong time, your friends will leave you and new ones will come, and you may feel like you are losing yourself and you may cry out sometimes.
Regrets hit differently, probably the worst of feelings one may ever have to face as they go through life but when these happen either of two things follows and I would recommend one and not the other. What follows is that we either hold on to the past or keep wishing we could go back in time and change things and do it better.
Or we learn to let go of the past, learn to let by-gone be by-gone, learn to focus on what's ahead of us, and above all else forgive ourselves for the mistakes we made whiles going through life. Is ok to have those emotional floods now and then, it is ok to cry when need be, and it is ok to feel down every once in a while. It only shows that you are human too.
But don't let it overwhelm you, don't let it control you, don't let it breed negativity in you. No, let go, forgive yourself, and heal. Time will continue to remain your ally, goodness will come, just try to be at peace with yourself. It is only a matter of time.