Son (m22) threatening to cut off contact with me (m65) over med school tuition

I paid all of my son’s expenses to get his under grad degree and he is now interested in medical school. Medical school will cost around $400k all in for living expenses and tuition. He is an excellent student but won’t get any aid since I make too much money.

I informed my son that he would need to take out loans for medical school since I am on the verge of retirement. I have around $2m in cash and another $1m in equity in my home so I could do it but would feel pinched. All of my friends who are doctors took out loans for themselves and were able to pay them back quickly.

He has threatened to cut off all contact if I don’t pay the costs and it honestly feels like huge entitlement and extortion to me.

Thoughts on dealing with this?