Time for Change. Good or bad idea ?

Hi there. This is a long story but i will try and keep it brief. I divorced my wife in 2007, both my sons ended up living with their mum but we enjoyed our time together on weekends and during school holidays. Life seemed reasonably normal. 

In 2016 my eldest son left mums home to start university. At the same time i was offered a job overseas but was able to return monthly for at least a long weekend to spend time with my youngest son who at that time had just turned 15. Overnight he developed a hand washing OCD and refused to touch anything in case of contamination. I thought this would pass but it just got worse and worse.

His mum tried to hide the problems at first because she didn't want people to know. She told stories to the MHT of how her side of the family were helping out with the increasingly difficult routines but in reality this wasn't true. She was hiding the truth.

I am not an expert but encouraged my son from day one in an attempt to turn things around. Briefly an example would be that i would monitor and time his hand washing whereas his mum would purchase larger size hand wash containers allowing him to stand and wash until his hands were raw. He would ask for help putting shoes on and i would in the nicest way possible refuse and offer words of encouragement saying "you can do it, youve done it since you were a small boy. HIs mum would instantly jump in to help and dress and wash him, sometimes helping him even to go  to the toilet. 

She is a loving mum and i know she is doing the best she can to cope but i see it that she has just been giving into the problem and feeding the rituals rather than challenging them. Until just over a year ago we would see each other regularly and he would stay at my house, we would walk the dog together and i tried to make things as normal as possible.

The last 12 months he has withdrawn and has refused to spend any time at my house or to go for a walk. We have met a few times in the kitchen of his mums house at a time when suits him. This is the only way i can manage to spend time with him. He does attend college (online now because of covid) and is studying music. So if he focusses his mind on something i believe he can do it. 

Over the past 4 years i have heard stories about care workers not being any good, about them being turned away at the door, about appointments being cancelled and lots more as you can imagine. In this time my son has been diagnosed with Autism, OCD and PTSD. Getting him the right help seems to be very difficult. but i feel i know him best and that i can help.

Just before Christmas myself and my eldest son visited my younger son in the kitchen as usual, blinds closed and in an environment he was comfortable with. When we arrived and entered the house my son looked so ill, so withdrawn and desperate. As we settled down we started to reminisce of camping trips and holidays where we all had a great time together. Like a polar bear leaving his winter den and thawing out in the sun i could see the same happening to my son. His mood slowly changed and for a long while we laughed and told stories, it was lovely and i didn't want to part from his company.

I am in fear that if he carries on living his life like he has with mum  since 2016 his health will remain the same or decline even further. I know his mum is struggling and i want make a change and give my son an opportunity, another path to perhaps help him get better.

To enable this to happen i need to give up work and be able to keep things ticking over, so i don't mind getting part time job. This will be the first hurdle. The second will be convincing my son to give up the comfort of living with mum, her always being there for getting dressed and other things and to live with me. I know this is easier said than done. Maybe its a non starter, i have no idea but what i do want is for my son to get better and to start being happy again and enjoying the life he deserves. 

So im interested to hear opinions, stories of people who have maybe been through a similar situation. I just want things to get better and am at the stage where i am willing to try anything. 

Thanks