I'm going to kick my step-son out
Do you have a reason for that?
Yes, and it's none of your business
It's okay if you don't want to tell me your reason, but kicking children out of a house is a serious decision to make. Your spouse should definitely be part of the decision, since they are his or her children.
You can't say you understand what I'm going through.
I don't, and I welcome you telling me more since I just want to help you!  But from what you've told me so far, I see no reason that your spouse shouldn't be a major part of this decision!