this doesn't seem that hard of a decision to make. u wrote u've played thousands of hands w/ this player so u should know him/her well by now. there is $159 in the pot ($12 preflop & $42 on the flop plus the $105 all in on turn) and u need to call $105. u r gettin 1.5:1 on ur money which means u need to win the hand more than 1 out of every 2.5 times or over 40% of the time to make the call profitable. just pick a hand range for this person (since u r supposed to know him/her that well) and measure ur hand against his range.
if u don't know how to do this then u def have a lot to learn yet. u could start by reading an article phil galfond (omgclayaiken) wrote not so long ago for bluff mag about hand ranges and what he called "g-bucks". i believe it's the simplest way i've ever read that concept explained.
link to article