There will be times when life sucks. As in the pain you feel will feel endless. All you will want is to go back and make it right. Spend more time, don't hurt, make it right, listen, be in the moment. Regret. You will have thoughts of regret whether or not you've ever told yourself that you have no regrets. When someone you love dies or you realized the life lesson after the barn door is shut and the horse is no where to be found.
Moment by moment, day by day you deal with the pain and do your best to distract yourself from the pain. Pain, hurt, regret will consume you. In an instant. You have to fight back. In your weakest moment you have to fight back. Don't do it alone- call a friend, see a therapist. But dear god, don't expect the person that you just hurt, don't ask him or her to make it better. Only you can reach inside yourself and start the journey to better.
I'm doing ok. And the rant above is only slightly referential and then from only a third party point of view.
Try, do your best, not to have regrets because if you live to old age, I'm talking late 80s and 90s, all you will have is the past. Have happy times on which to reflect. Dependent on someone to take care of you- fix your meals, get you out of the house, take you to the bathroom- you don't want to have regret sneaking up on you. Your life will suck enough.
This is my only life. I will do my best to appreciate each moment I have. My amazing sisters, the amazingness of finding love with someone who dealt with me at my worst. I pined for 16 years. I should have lived my life for 16 years. I could have not pined, not cried over lost love and still have reconnected with Fisher. We're not back together because I shitted away great moments of my life because I was obsessed with him.
Appreciate all the good- in yourself and others. Do your best to be a better person. To have pure love for another. Plan for the future, but don't write it in blood. Write it in pencil or have some white-out handy.