My mother raised me alone all her life. At one time she even worked 3 jobs to support my sister and I. But recently, she has been disabled and hasn't worked in 2 years. In those two years she has grown into a child. More immature than my sister and myself together. I, still being stuck here, naturally took it upon myself to set the example my sister would have to follow.
So, let me get this straight. Your mother took care of you, but got unwell for the past 2 years. Now you're abandoning her to set an example for your sister?
Yes, this is the absolutely the right thing to do. Frankly, you sound like you inherited your father's views on responsibility, so that shouldn't surprise your mother much. So you go do your thing and leave, and it will be far better for both you, and your mother and sister.