My father's sister was a raging alcoholic - in an extremely literal sense... When she did not have alcohol, she was verbally violent. If you deprived her of alcohol she was physically violent. She was also physically handicapped and endured a lot of abuse from her peers as a youth - which reinforced her combativeness.
When she was in her late 40's, she was out on a camping trip with family. She fell asleep in a folding chair, it tipped over and she broke her neck. Paralyzed. For the first several years after the incident, she had some use of her arms, but she eventually lost her arms too and was admitted into an assisted living residence until she passed away a couple years ago.
Living with no control of your extremities is awful. You're a prisoner of your own body and is a fate worse than death. It's easy to question "how could an all-loving God allow such a thing and what purpose could something like that possibly serve?" Well, what it ended up doing is spurred about 40 family members to provide greater love and support to her, each other and others - be better Christians. So in a sense, she was a sacrificial lamb to improve a large group of others. It also sobered her up and brought greater clarity to her life and closer to God. Had she not become paralyzed, alcohol would've likely continued to consume her - which could've likely resulted in her eternal death. Paralysis in her earthly life became a gateway to eternal life.
So regarding your handicapped child, I'm willing to bet that caring for your child has altered some of your perspectives and molded you and your family into more selfless people. It taught you valuable life lessons that you subsequently share with others. It has also brought trials and obstacles to overcome - making you a stronger and more resilient person. So in a sense, your child's handicap may have improved the lives and perspectives of you and dozens of other people.
