His call raise on the flop doesn't make much sense to me with this many people in the pot.

I think he is as likely to have an 89 for a straight as he to have the full house/quads on the turn.
77: 3 ways
66: 3 ways
55: 1 way
full house/quads total: 7 ways

89: 12 ways
straight total: 12 ways

If he has the straight he takes away 3 of your lower end straight outs and 1 of your higher end straight outs and leaves you with 11 outs for the river. In which case your getting close to the right pot odds to call.

If either one of them has the full house or quads then your not getting the right pot odds to call.

Also someone could have the higher flush draw here. Taking way those 9 outs.

I think that you can fold on the turn. As for the flop, I don't mind the way you played it. The first raise had folding equity and then you had pot odds to call the reraise. I would have favored just calling on the flop rather than trying to semibluff 3 opponents that already called a small bet/raise.