Well assuming all your outs are good, you have 14 total outs (8 to the flush, 8 to the straight, -2 because of straight flush possibility), and a 0.29 chance of hitting any of those on either the turn or the river if you consider every possible remaining card which roughly equates to (0.29*0.71)*2+(0.29)^2 = 0.4959 (this isn't exact, just a simple estimate - I don't have a scientific calculator to hand and it's late over here ). Pot is 51k total if you call (couple of k more if there are antes, doesn't make the world of difference here), 16k more for you to call, so you need a 0.31 chance of hitting on the turn or the river for calling to be statistically correct.
However, this is assuming all your outs are good, which in this case may well be not true, the other players (Player A more likely, Player B is probably tilting, definitely pot committed and could have almost anything) could easily be holding something like AK/KQ of spades, eliminating almost half your outs and making your odds
to call much worse.
There are a couple of other factors to count in such as the possibility of runner-runner spades counterfeiting your flush or fluke two-pair outs for you etc. etc. but they have only a tiny effect on the odds anyway.
I call anyway here, given the probable odds and the money I already have in the middle.
About the 4k bet, if you weren't willing to call a push, which is player A's probable action given the range of hands you put him on, you shouldn't have bet that. I probably push myself here and beat him to it, hoping to throw him off AQ/QQ/JJ, but knowing I have a strong draw if he does call.