My son cries uncontrollably and I don't know what to do

My son is 9 years old and normally he's a very happy child. Some background : when he was a year old, he was diagnosed with cerebral palsy (spastic quadriplegia GMFCS IV) He is very smart and came to me at a young age asking why he couldn't do things the other kids his age could.I've always been very honest with him about his disability status and given him all the information I had. He is a part of his IEP meetings at school and he's active in setting his therapy goals. I want him to feel empowered in planning his future.Recently he's been expressing some sadness over "never being able to walk" Last night he broke down in uncontrollable sobbing for nearly an hour. He's told me he hates being handicapped and that it's not fair.I've told him about great people who live full and happy lives with his level of disability, but I have to admit, being in the chair sucks for him sometimes.When he gets upset I have no idea what to say or how to address his feelings. Last night I held him, told him I love him, and that I'd always be there for him. My other kids adore their baby brother. He has a strong support system and a great school with other kids who are very caring, both typically developing kids and kids with orthopedic impairments. As far as I know, there's no bullying taking place.I want my son to feel positively about his future. He's smart and capable of so much and I don't want his disability to take any of that away.I need help. I'm not sure what to do. We have clinic coming up next week, but I thought maybe other parents would have advice. via /r/Parenting https://ift.tt/2GaInHO