I'm sure she's happy for him to play football, but how is she selfish for wanting her kid to go to a certain school? Plenty of parents are never happy with the decisions these kids makes, and the ones who choose schools that don't play sports. She's allowed to act however she pleases, it's her life and her son.
My step dad's family was pissed off I had no desire to go to UF and that I chose FSU, it's apart of life people especially your parents won't like every decision you make. I'd be mad too if I had a kid who passed on the local school nearby for another school that was out of state.