My ex pays for 18 yr olds tution.My son also qualified for grants. I claim him as dependent. Who uses 1098T credit?He worked last year and wants for me to not claim him?

My son did work half of last year. He also put my income down to qualify for grants. But now his dad is saying I didn't pay for his college so I shouldn't even claim him and let my son use the 1098T so he can get most money.