Unreasonable, or is it me?

My ADD husband and I separated at the end of April. I just couldn't take it any more after 10 years (half of which he hasn't worked). In December, I had learned he had been posting on sexual forums, even including his photo (face). I thought he would never cheat on me, but there it was. I was very specific about what I needed from him to stay in the marriage after that and, when the deadline rolled about and he had done none of the work, I had to ask him to leave. We haven't given up hope of reconciling, although I will say that I haven't seen much from his side in the way of action for improvement.

Anyway, now he is staying with his parents and his 80 year old mother just had hip replacement surgery. His father, who is even older and who also is very ADD (though not diagnosed) can't do a lot to take care of her. She wakes up at 4am every morning--has for years, decades probably--but although she needs help (at least someone conscious in case she falls!), no one will get up that early for her. The ex says it is not reasonable to ask him to do that and his father, well, who know what he is thinking. Now, he (ex) does help out in many other ways, to be sure, but that point seriously concerns me. Am I crazy, or is getting up at 4am for a couple of weeks to help your mother not too much to ask of an unemployed person who is already living in the house? He literally said that she was getting up at 4 because she was too belligerent to change her sleep schedule before her surgery. I don't believe that--I think she's just overwhelmed with going from a self-sufficient woman to someone who has been through a really physically tough year, culminating in this surgery. IMO, who cares if she is being rational or fair--she's 80 and needs help and I'm disgusted that no one in his family will put themselves out for her in this, most of all him. 

I tried to explain to him last night that his saying "It's not reasonable" and "I can't get up at 4" concerns me. I tried to do it gently and to talk about my feelings and not make him out to be a monster or anything remotely bad. I said that maybe she just needs someone to just be there for her, rational or not, like we all do sometimes. Very non-judgmental--just trying to get him to be compassionate for her needs. Didn't work.  He got angry.

If we are to have any hope of reconciling, I need to know that he will be there for me. If he won't be there for his own mother when she really needs him because HE has decided that she is being unreasonable (judging her although he can't bear to be judged himself!), then, well, what about if I got sick and needed him? How am I supposed to believe that he won't judge whether I am being reasonable? I don't think that should even be a factor--if you love someone, you are supposed to be there for that person without judging whether or not what they are asking is reasonable, especially in the case of medical issues.

Am I being unreasonable? I really don't know anymore...