I'm going to get my husband tested for autism behind his back
Would you leave him if the test came back positive?
I don't know. He has serious behavioral problems and I don't know what else I can do.
Wanting to know if something is wrong with your significant other makes sense, it can help you to better support them. But going behind his back to find out is really rude and inappropriate, especially because it has the potential to change your relationship. Sit down and talk to him about it if it's really that much of a concern for you and work through it together.
Still, I want to know. The reason I want to know is different from what you are thinking. I want to leave him if it turns out that he's retarded.
You shouldn't call your husband degrading names like that. Even if he turned out to be autistic, you still went behind his back so how would he feel finding out you betrayed him? How about talking with him first, and discuss any symptoms if he agrees with you.