A therapy tub for justin

My son Justin is a young adult who is disabled. He is autistic, seizure disorder, developmental delayed, post traumatic stress disorder, and my life. He was abused at a group home many years ago ,where I had to place him as I had to have surgery. Things were done to him that complicated everything. The only thing that seems to truly help him is water. He is a big guy at 6'4 and 300 pounds, but he is a good and loving person. The problem is my bathtub, a garden\soaker tub is falling apart..Cracking...I need to replace the tub and am desperately trying to get help to do it. Water calms him...Please help me help him. Anything you can do is so amazing!I am a single mom trying to keep my son calm...His older brother is trying to patch the tub but I fear it is beyond patching. Anyone who knows me knows I will do what I can to help my son..But I am realizing I need help. Please..If you can't help...Please post.