Ask God for everything your heart desires. Pray and pray hard. Be serious and keep at it. God will listen and He will answer. The answer may be different than what you want, but if your heart seeks the very best for the one you're helping, God will find a way.
Understand that Jesus is the ultimate Caregiver. He has felt every emotion, every frustration, and every bit of sorrow not only for the one receiving your care, but for every person who has ever walked on this planet. His emotion, frustration and sorrow are multiplied by billions. He understands where you are.
Remember that this world is not our home. When we accepted Jesus as our Lord and Savior, we instantly became aliens in a strange land. Jesus made it clear. In this world we will always have trouble, sickness, evil and death. So He has prepared another place for us, our real home, where we will find that none of that exists.
Believe that God loves you both. God is love. He has chosen not to end sickness and sorrow in this world because this world rejects Him. But so that both of you might have happiness forever, He came and walked among those on this earth, then gave up His life so that we might have a new life with Him. That is the ultimate act of love. Everything else is but a shadow.
Rest in Him. Don't try to be the solution yourself. Give it all to Him. The hurt, exhaustion, sorrow, anger. Whatever the situation, let God be God. Trust in Him. Rely on Him to decide what is best. And then rest in that decision.
Watch His power grow in you and then discover what you can do. A lady once wrote us about a sister who had brain damage as the result of a car accident. Some years after the accident, that lady gave birth to a son who was severely brain damaged because of oxygen deprivation. "It was a trying time for me but you know what I learned about myself? First and foremost, I can care for a head-injured person; in fact, I can care for two head-injured people and retain my sanity." In times of need, God gives us the strength to do what we could never have imagined doing before. As another wrote to us, "Trouble is an inevitable part of life. When tragedy strikes we all need lots of friends around us. The Lord does not want us to go through these paths alone. That is why it is important to cry out to the Lord and allow Him to wrap us in His loving care.
No difficulty is too big for God to handle.