TLDR, I bluff shoved a flush river vs an old man coffee who snapped me off with an overpair. I wasn't on tilt, my image was fine.

I put him on an overpair. Everyone knows old man coffee's don't fold overpairs.

But, when that scare flush completed on the river, I snap made my decision in my head to shove. (although it wasn't a snap shove)

Any books / resources I can use to help slow my thinking process down, and not be so reactive at times?

Begin and end by understanding the value of moment-by-moment awareness. The value of observing what's happening externally and the affect this is having internally.

This is a real alertness.

And unfortunately no resource or book is going to grant you this special skill. To understand this as a fact, is a crucial thing if one is really interested in this matter.

The breath, that's where you slow all things down in life. Take a deep breath, follow it in and out, be in the moment.

i think taking plenty of time on serious decisions is very profitable. even if its 30 seconds+

sometimes the difference between winning and losing a large amount of $ is just ten extra seconds of thinking, reconsidering, detaching etc

its not selfish to time bank on these big decisions, you are entitled to a minute of thinking when there is money on the line

Tell yourself that in the future any time you are going to make an all in bet you will stop yourself (maybe take a deep breath) and double check your reasoning in your head and only make the play if you are sure its a good play.

I don't think it's about slowing yourself down in this case . It's more that you don't want to lose the hand so you make the stupid shove because that gives you hope even though if you did slow down you would admit it was very -ev . So I feel like you don't WANT to slow down in this case because then you would have to be logical and accept the loss of this hand
It's like compulsive gamblers when they are in the midst of a losing session they just keep going because it's much less painful to keep going (there's still hope) than it is to stop and face up to the losses
I don't know the solution .. I just think it starts with getting to the root of why you want to try that desperate shove rather than calmly think ok I lost this hand and it would be stupid to try and win it from this position

tbh if everyone knows that old man coffee will never fold OP's & especially in what i presume to be low live stakes plp don't go to casinos to fold, it's great that you perceive your image at the table but you must learn which players are more analytical such as younger plyrs with hoodies & or headphones w/ shades, pick your spots and this is just a lesson you must learn & that's why you must bring an extra buy-in or two