Good job
800 rating beats 2000 rating in blitz

Good job.
I can't believe he hung his queen like that. b4?! is an unsound gambit, and after your 5 Nb5?! Qa5 6 Qh5?, my first reaction was ...Qb6 but then i realized ...Nc6 just develops a piece and guards the queen, and I checked stockfish after looking at 6...Nc6, and black is just crushing after the correct knight move. (Keep in mind it's now *white's* queen that is now completely hanging, and the b5 knight is now pinned). I guess 6 ...Qb6? fails due to 7 Bc4 e6 8 Qe5, which is rather awkward for black after 8...Na6 (though black is NOT worse). But after 6...Nc6, 7 Bc4 e6 leads nowhere fast for White, except to a positionally lost game.
After your 4 b4?! Qxb4, your best chance at getting something for the pawn is the tempo-grabbing 5 Rb1 Qd6 6 d4, which is very similar to some d4 opening sidelines (usually London/Tromposky/Verasov systems) where white sacrifices the pawn on b2.
This is probably my best win on chess.com