I recently got really grossed out by a disabled person?

Just last sunday, my boyfriend and I joined his parents and some family of his at a local bar and restaurant located on a farm, to watch my boyfriends cousin sing. We were sitting at our table, when a man, a woman, and a downs syndrome woman walked in. The down syndrome woman was clutching the older woman's arm as they walked, I suppose her mother.

She had a strange and quite creepy expression on her face, and her face seemed somewhat deformed, like even more disproportionate that the usual downs syndrome features are. She was walking very slowly and clearly couldn't walk or sit down or stand up by herself, as this woman clutched to her mother almost the entire time. Later on, after observing the trio's behaviour, I notice that the man is her husband! This sickened me for many reasons but mainly because I feel he would be taking advantage of her situation, and wouldn't it be like marrying a child?

Anyway, this disabled person had no comprehension of personal space of personal hygene, apparantly. She looked dirty and continued to give me the death stare all damn day. She had a baby bottle filled with water she was drinking out of, and she repeatedly drooled allover herself when drinking out of her baby bottle. When I saw this, it kind of made me sick to my stomach. I've always been fairly tolerant and sympathetic towards the disabled, physically disabled anyway, but the mentally disabled, the ones who drool, stare, have no manners and always look dirty, freak me out.

I realise this is probably a horrible thing to think of someone who didn't ask to be born that way, but jesus christ they give me the creeps. Does anybody else feel intensely uncomfortable around mentally disabled people who are incapable of functioning like a normal human being? I would never openly be disrespectful or rude to any of them, but they really make me feel uncomfortable.