Our table broke and we are now playing heads up to close the night out. The villain and I have played hundreds of hours together and have a mutual respect for eachothers game. The villain is loose and very agressive.

Button (~$750)
Hero (~$460)

Preflop: Hero is BB with 4, 8.

Villain raises to $9, Hero calls

Flop: ($18) 4, 3, 6 (2 players)

Hero checks, Villain bets $15, Hero Calls

Turn: ($48) 4 (2 players)

Hero checks, Villain bets $50, Hero raises to $100, Villain calls $50

River: ($248) 9 (2 players)

Hero bets $80, Villain instantly pushes all in, Hero...

Comments and suggestions on all streets welcome

Call.
Make a bigger raise in the turn.
Don't call raises out of position with 48 if you are not going to call after hitting trips.

I don't understand either your turn or river bet. The turn C/R was way too small. I'm sure that you'll agree that making it $50 more to call in a pot that had grown to $198 just doesn't make any sense.

Then, although you bet $100 on the turn, you bet only $80 on the river into a pot that was now $248. With that bet, you now also had about 45% of your chips in the center of the table. That, it seems to me, is pretty much the definition of "pot committed," especially after a river card that does not complete any of the draws presented by the turn. If you thought you were ahead enough to C/R the turn and value bet the river, there is no reason to fold now.

You're playing heads up, you have a well hidden trip 4s. As played, call and curse if he had 99.

Does anyone not think that my hand is face up by the time he makes his river raise? What do I beat other than a bluff? I don't feel he would shove the river here w/ something like 9-6 or AA.

I new immediately after the hand was done that I made bet sizing mistakes and that lead to being put in a tough spot. I know I put a large % of my stack in but I just don't know what he would shove on the river that I would beat.

As played do you still call???

tough spot here..
i would call and be so pissed that i played so bad if he has you beat..

Yes your hand is pretty much face up with the checkraise. I mean.. this hand has to involve history - what is your image to the villain? How does he tend to play you and does he generally give up when you show aggression? I mean does he really think your min checkraise could be a bluff?

Also, fold this preflop. And call or checkraise big enough to look bluffy on the turn with the intention of getting it all in.
Also, fold to river raise barring a lot of history - ie: you need to know that he is capable of smooth calling a checkraise and then bluff-raising. Not many people are capable of that.