Definitely a stackoff on the flop.

Yup. This is a stack off. You have an overpair, you have a nut gutter, you have an excellent price. It's high variance, but it's (almost) certainly profitable.

The equity you have said being 20-22% looks wrong to me and intuitively this looks like a clear fold. I agree if we did need only 20-22% equity, this would be a stack off. How did you get this number? Lets have a look at the way I would analyse the situation. Please let me know if you think I have made any mistakes... I don't do this sort of calculation very often! 

The pot is 8.95 currently. The 3way main pot will be the current pot size plus 3 times what the hijack has left, 8.95 +(3*10.53) and we will be risking 10.53$ to compete for this pot. This means that 3way we need equity of 10.53/(8.95+(3*10.53)) which comes to just under 26% equity in the 3way pot. 

The heads up pot will be the small blinds stack minus the hijacks stack as we have them both covered, which comes to 3.42$, so for the side pot we will be risking a further 3.42$ and will want to have greater than 50% equity to break even. 

3way things are a bit more complex and we could do a simulation if we knew both of their ranges and try and figure out the exact equity we have, but lets just take a more simple approach. I think we are almost always an equity dog versus the small blinds range in the heads up pot, given we are flipping or a dog versus draws, a dog versus most pair+draws and a massive dog to made hands. To make up for this equity disadvantage, we need to have greater than 26% equity in the 3way pot, which, given the board texture, where it is very likely at least one player has a strong draw, either a flush draw or a straight draw, and given we are drawing fairly slim if either player has a made hand better than our over pair, seems incredibly optimistic to me. 

"*sb 32\15 donk bet 14% big sample"

14% donk bet is strong, it's 3 way pot and because villain is donk potting it's even stronger. This is fold.