Regret is not bad. There is nothing wrong to have regrets. It reminds us that we can do better. Regret helps us in facing situation better in future. You made a mistake or made an accident and now you regret it. It is true we did badly but we will never repeat it again as we now know what was correct for the situation.
If we have goals and dreams, we are bound to make mistakes. We regret them. And we learn from them. Regrets are an important element in reaching our goals.
Having no regrets means, we do not accept our faults. This is arrogance and we are sure to fail.
Do not burden in the weight of regret. Try to rectify. Accept and move on to change things.
Learn to deal with the pain of regret and do better next time.