I'm going to go over to my parents house while my in-laws came over
What is your reason for this line of thinking? What's the reason you want to go over to the house?
I don't like my in-laws. They treat us always like children
Hiding from in-laws that are treating you like a child seems like a childish thing to do. You don't have to stay for their whole visit, but it is rude to not stay for at least a short time.
I'm going over to my friend's house.
Your in-laws will think you are more mature if you visit with them. This may earn you respect with them.