Question about defensive driving: if some reckless driver pulls in
front of my car trying to make a turn, and there is no time to avoid
hitting his car from side, what is the best option, to apply brake
pedal in ANY situation or to floor the gas pedal so enough power toas
to generate  hit his car and reduce the impact strengh for me and my
passengers. Since my car is very heavy (BMW 535i), I tend to think it
might be a better option for safety of me and my passengers. Please
advise where can I find online resources for defensive driving tips.
Thank you.

A slower speed at impact will certainly do less damage to your car,
and more importantly to your passangers than a higher speed.  Any
reduction in speed you can create by applying the brakes will help the
situation.

The only benefit to speeding up immediately before impact is to raise
the front of your car.  This could potentially be good if you are
about to hit a deer (so it doesn't end up going through your
windshield) or a high sitting truck that the hood of your car could
potentially wedge under.
But in both of these cases, you must weigh the cost of the greater
speed with the benefit... and unfortunately in a split second decision
your analysis will not be great.  So being brake happy immediately
before any accident isn't a horrible thing.