Don't eat. Chestnut looks moldy, but it looks good inside, but it may have gone bad, just because the skin is exposed to the first mildew, and moldy food is easy to produce aflatoxin, which is a strong carcinogen. People will be seriously poisoned and very dangerous if they eat it. Don't take the risk. Burn it or bury it.
Aflatoxin can be detected in seeds and processed products, dried and fresh fruits, condiments, tobacco, milk and dairy products, meat, fish and shrimp and animal feed, and peanuts and corn are the most easily polluted.