I'm a single Dad dating a single Mom, and I seriously dislike her child what do I do?

[Needtoask]

We have been dating for 8 months.
She has one son (6); I have two sons (6.5 & 9)
They are close in age.
Her son is very smart but seems under developed emotionally. He puts on this whinny baby talk voice when he isn't getting what he wants.
I have watched him lie to his mother; hit other kids without provocation, including a three year old little girl.
I have a very strong connection and chemistry with her, but I want to run the other way when I even hear her child’s voice on the other end of the phone.
I really like people and other people’s children and have even dated another woman and enjoyed time with that woman's two sons.
I honestly do not know what to do. I do not want end what we have but know her child is part of the package.
Thanks for the feedback everyone.

I have talked with her about it at length. The first conversation was total denial. After more feedback from his teacher and aftercare she felt I was on to something.

She brought him in and he is now on Prozac for PDD (or is it DDP), not quite aspergers.

It appears to have helped but I don't think I can deal with the extra work invloved. My youngest son has had his own issues and it's been a lot of work.

Her sons father is out of state and see him on his birthday and two weeks out of the year.

My Ex and I are friendly and actively work together to be consistent with our boys. My Ex has had substance abuse issues that seem to destablize things from time to time. She tries hard but it's been an issue.

I think from a compatiblity stand point if it weren't for her son I would say I have never felt so satisfied with anyone I have dated.

Her son has an uncomfortable look on his face 75% of the time & lies about things he doesn't need to
I am still wanting feedback if there is any out there.

Has anyone else on here been in the position?