i have three, the oldest has sn (autism and severe learning difficulties).
it is a lot easier to manage and get organized on my own! yes it is a daily slog, but when things run fine it is fine.
i could not manage with a demanding, controlling and needy adult as well.... when i did so it was literally like having four children. and being controlled by one of them.
fitting in with contact has been difficult as exP has not turned up on time etc etc tho he seems now to have got the message that timing is everything. especially with autistic child.
if i didnt have to worry about exP and him turning up or not; getting abusive texts or not from him etcetc; him moaning and complaining "poor me" by text - the text msgs are on phone to the kids so i have to read them in case they about changing contact times etc - (and spending over the overdraft on a still joint account) then the daily routine would actually be easier. but as younger kids get older and can deal with contact directly, themselves, hopefully it will get a little easier.... or maybe not!
step by step...
i have reduced my work hours slightly which has helped a lot on the day to day.
food shop online, etc etc it all helps.