My Disabled Cousin

My cousin suffered a car accident many time ago and left her physically disabled. She has problems in moving and needs help with the stairs and to get in the shower.
I've helped my aunt many, many times in getting in her in and out of the bathtub, but never stayed to wash her.
Some weeks ago, my aunt asked if I could stay with her during the weekend and take care of her.
Although my cousin is disabled, she can do many things alone and I was just there to cook and help her to move around the house.
Friday everything went as any other day and Saturday was also running as expected.
But during lunch, she spilled the soup all over her and, naturally I had to help her changing clothes. Normally it's my aunt that does this things, but I didn't have any choice and had to do it.
I got new clothes from her room and started to undress her... I always have seen her dressed until now.
That day she wasn't wearing any bra and not only her breasts were bigger than I thought, but really beautiful and almost perfectly round.
I got totally surprised by it, but kept undressing her until she stands with nothing more than her painties covering her hairy pussy (apparently my aunt never thought in trimming it), and at this point I was very hard and my shorts can't hide it.
She wants to see it uncovered and ask me to put it on her hands.
I say that probably it's not a good idea, but she insists and remind me that she's still a woman who hasn't seen a cock in a long time.
I take my shorts off and let her have it on her hands. Due to her condition, it's hard to get a good grip, but that didn't stop her.
Put it in my mouth, she said... I didn't blink and let her blow me until I grabbed her head and exploded inside her mouth and she swallow all my load and kept sucking it.
I laid her on the couch to rest a little bit and we had sex two times.
At night (in her bed) she wanted to try anal.
In the beginning she had lots of pain, and wanted to quit, but we ended up in doing it again.
Before my aunt returned from the weekend, we talked about it and agreed in just doing it again, if we're alone again and if I'm still single.
Last week I was on my aunt house for a short visit but my cousin swallowed another load and we're going on vacation for a week next month.
I know that somehow I'm taking advantage of her disability for my sexual fantasies but she also wants it and doesn't care, because she's also have her fantasies fulfilled.