Hello - advice needed

Before I start, I apologise now for any of my comments that may come across as derogatory to anybody with Asperger - I am lost and lonely in this and am struggling with something I don't understand.

My OH at the age of 54 has just been diagnosed with Asperger - he's always known from an early age that he "felt he didn't fit" - his words not mine.   I've known OH since I was 12.  We started a relationship in 2018 I was 50, he was 52 and I moved in during the first lock down.  He has 3 children SS19 x 2 (twins) and SD14, I have a DD who is 22, who lives in my house with her BF.  I am at my wits end, although the diagnosis has ticked one box and explained so many behavioural issues, it opens up so many more.  

Since moving in, there was a massive shift in our relationship, the man I "dated"  became someone I struggled to recognise.  OH is very needy, despite enjoying his own company and solitude, he is unable to make decisive decisions, if he asks for help, he then challenges the decision I've made.   He lives a very set routine, has poor personal hygiene, despises wearing clean clothes, will only eat beige food.  

He doesn't understand his role as a parent, does not discipline, encourage, lead by example, refuses to talk to his Ex so all communication is through SD14 (who is also on the spectrum).  He favours SD over the twins and is very open about this.  He doesn't understand emotions, mine or his kids and we've  been told we have to get on with it, except for SD14 who has him wrapped around her finger.   She is with us every weekend, all weekend, and 50% of any school holidays.  As soon as she arrives she is by his side, literally, until she leaves.  I am relegated back to the house, as OH doesn't do any house work at all, no shopping, cleaning, cooking, washing, changing of beds, decoration - nothing. 

He enjoys social interaction and TBF is much better now than he was at the beginning.  He runs the family business, but won't change anything, despite its growth, as it's always been done this way, and is worried about his Dad disapproving.  Until very recently his mother ruled and controlled him (I believe she has known his diagnosis and chose to ignore it by enmeshing him in the business. ie keeping him at home).  I now work in the family business, as it's also my background (farming) and slowly things are changing.  

I no longer recognise myself, I was a very strong independent woman.  I had a very successful career in the corporate business, in the 30 years I worked there I became a successful manager.  An abusive marriage, the death of my subsequent partner and then the death of my darling dad made me realise there is more to life than what I was doing.  I gave up full time employment as I knew it to become the co-ordinator of an annual farming event.  I was at that stage in my element.  Now I question my sanity most days, feel miserable and worst of all have hideous arguments with my OH at his inability to nurture a relationship, parent his children and to basically stand up for himself.  

I am in no way materialistic, clothes, make up turn me cold, I am me - however, my last birthday I was presented with a bag of Maltesers and a card he'd bought at 11pm  the night before from Tesco - I asked why not flowers or wine / Prosecco - his response, but I remember you eating Maltesers.  Christmas  - a coal scuttle, I do the feeding of the stock and he thought this would help (had his business been on its knees, then yes, I could understand buying such a practical present, but we're talking a million turn over a year), a dart board??????  his explanation, we have our own family one, I thought you'd like your own.  Microwaveable hand gel warmers (I know you won't like these, but SD does), a box of cookies (I know you don't eat things like this, but I liked the box).  I was heartbroken as my daughter had a list of things she knew I'd like (he had been told by both of us to get in touch with her for ideas) - I had directly told him I'd like some earrings and we could go together to buy them. 

There is no romance, he doesn't like kissing, it's dirty??? I now understand, it's linked to sensory, but his idea of a sexual relationship has at times scared me, having read a number of articles, it starts to make sense, but doesn't help where I am right now. 

I think, what I'm asking is 

can we have a heathly relationship

will he ever be able to separate me from his mother and his daughter

will I always have to be the decision maker

will I always be a surrogate Mum to him, partner, decision maker, cook, cleaner, laundry, shopper, decision maker, parent to his kids when here

Finally, who will look after me?????  I think that is my biggest issue.