It takes two to work at a marriage, and it sounds like she isn't. It will be more painful for you to suffer a slow death to the relationship if she doesn't want to fight for it.

Do not resign yourself to this, there will be life after and you do not want the regrets and bitterness of handing her everything you are entitled to as your partnership ends and she moves on.

The tone of your post lacks empathy and penitence.

You should probably take steps to educate yourself about her child's disabilities in an effort to avoid a repeating scenario.

People are different, everyone has struggles, visible or not.

Grow up.