getting crushed in the opening please help

Someone tell me what is the best move for black here?

Black wasn't supposed to capture the Knight.

Don't take with your knight move your bishop to c4 instead

That's what I do at least

Chess Openings Resources for Beginners and Beyond…

https://www.chess.com/blog/RussBell/openings-resources-for-beginners-and-beyond

Bruh i think these resources solve chess....

Black is somewhat worse here already, as the White Queen is dominant at d4, and cannot be easily kicked away.

The right move is 5...Bb4 (in place of 5...Nxd4) but there is also a good surprise move, namely 5...Nxe4!?

I'm a 200 and your IM so I can't be saying anything.

In that horrible position, caused by developing white's Q into a threatening position, I'd play ...d6. Something more active, like ...c5, looks poor for black after maybe Qe5 and Nb5.

It cannot go very well. Actually it is a Philidor, Antoshin Variation, a full critical tempo down for Black.

This is the line here:

and this is the Antoshin line, which is regarded as slightly better for white:

Can you explain the point of Bf4 there, is it to support an e5 break? is Bg5 not preferable because you never want to take on f6, and you can stop d5 without it?

Yes, Bf4 intends in many cases e4-e5, and it also discourages ...c6 and ...d5 (although one of the most chaotic Antoshin variations goes 6.Bf4 Be7 7.Qd2 d5!?). The bishop does nothing at g5 when there is an opposing one at e7.

Makes sense, I think the (mistaken) instinct of myself and a lot of players is to play Bg5 to threaten removing a defender of d5 if it's ever played.