What’s the time period? My wife is from the rural area of the PI and says monkeys are pretty much rare, endangered, and FAR more valuable as pets. Someone probably sold you cat, rat, or dog and told it was monkey meat.
I spent some time at the Subic Bay naval station on two westpacs in the early seventies. There were several vendors selling the shish kabobs of the mystery meat in the evening, balut in the morning.