How long can cooked prime rib keep in the refrigerator?

My wife made a beautiful prime rib on 12/17 and we've had the leftovers in the refrigerator ever since. (16 days) She's cooked some of it into a different leftover dish etc. Which was great. But today she took the rest of it and cooked it again in the crock pot and is shredding it to use in tacos or something similar. Is this safe? It's been in the refrigerator for over 2 weeks. Pleas advise. I don't want us to get sick...at the same time we don't want to waste good meat.