Absolutely not!
Your past is something that you cannot control in the present right? So why bother over something which can not be changed. However, at the same time, you can control your present and the future. So lessons learned from the past should be kept in mind, such that mistakes done in past aren't repeated. There's no need to feel sorry about the past because every experience good or bad teaches us something and contributes to inner growth.
Quote I heard in Kung Fu Panda “past is history, the future is a mystery but the present is a gift, that is why it's called present”
Shit happens but it’s wrong to be a victim of one’s bad past.
The thing is you just can accept the truth or think about or cry on it until you break yourself down to the last bottom. It's always the right time to accept the truth and move on. We came into this life just to explore things, experience the moments, and not just sit in the corner and cry like a kid. We deserve a good life and we should try every effort to make it good.
Once you start accepting every moment as an experience in life, you’ll never say it was a bad past. It was just a bad experience. and I will make it well next time.
Ups and downs are the two only necessary factors of life. Accept it.
Life is beautiful, don’t waste it regretting things.