don't let queen e2 be played

Try 0-0-0 instead - don't castle into White's attack.

And how would I do that?

20. ...f5 is correct. Black is fine there. To further understand the position and how to defend it put it in an engine and see for yourself. White has no attack and black can get an advantage even if played correctly.

One example would be:

Vincent, try downloading, or buying, a ChessBase Frtiz Opening Trainer. They have some wonderful CDs on lots of openings, I did see the caro-kann before.

You're a video creator yourself, am sure that you prefer studying from videos as well that's been made by some strong GMs. Perhaps it's better than buying a book nowadays to some.

I could tell you to use the lines in ChessBase, but that's not the best way to learn, as it doesn't have any real explanation, just statistics.

I hope that I did help, and sorry, but am not a Caro-kann player.