Completely not sure what to do here...

We are desperately trying to Potty Train Will. He refuses to poop in the toilet though. Completely stubborn.
I can sit him on the toilet every 15 minutes and still he will go in his underwear. He will Pee, won't poop. When I ask him where we are supposed to Poop, he tells me in the Potty. He can re-iterate but he still just don't do it.

Finally after weeks of desperation, I called Momma crying. I just don't know what to do. She said if he is able to tell me where to go, and has been using the bathroom, maybe its time to start punishing him for pooping in his underwear. I tried it.

Now he is afraid to tell me when when he has an accident. We just asked him if he had to go and he completely started freaking out on us. I had to drag him in there. Turns out he pooped.

I am completely lost as to what I should do, and now I feel awful.