OK.
I have 3 teens aged 18, 16 and 13.
It is bloody hard being a parent of teens, but all of this crying over the baby they were is too much.
And I believe it feeds into the grumpy person they are now.
Stop looking at the holiday snaps of smiling 9-year-olds. They are not 9. Look at who they are now and embrace it.
Embrace the change and help them - compliment them on their new teen choices (hair, make-up, clothes) even if you hate them. Let them know that the evolving new person they are is just as great as the smiley kid that they were.
Learn to talk to them differently, more as a peer, listen to their opinion and engage with it.
Don't stop parenting, in fact parent harder, and insist on things like eating dinner together, helping with chores etc, but be open to renegotiate things that matter to them, and deliberately work towards independence.
Above all, they need your love now more than ever. They hear things 100x more negatively than you intended it, so be massively proactive about saying good things to them.
As they leave for school every single morning I say - Have a good day, I love you. Sometimes the door is then slammed in my face. That is fine. They still heard me.
Let the grumpiness slide over you, don't engage.
Enjoy them. Teens are great, bloody hard work, and at times a thankless task, but they are great.
ds is now 18, he is off to uni in Sept and I am so proud of the thoughtful kind lovely man he has become. I had absolutely no assurance of that when her was 12, 13, 14, 15, 16....