I'm going to cancel the plans I made with my dad.
Why are you canceling your plans with your dad? Is there something serious going on?
Because my dad is being weird with me, my mom is being sneaky with me, my brother is being offensive with me and my cousin is being overly happy with me.
While you might be currently annoyed at your dad's behavior, it isn't appropriate to cancel plans on him because of it. It'll not only be rude but also disappointing since it's expected that family members spend time with each other. Instead of canceling your plans, you should talk with your dad and explain the issues you are having with your family so that you can begin to work on resolving those issues.
No I'm too sad that I'm not going to hang out with my dad to talk about it.
I am sorry that you are sad but pouting about it won't fix the problem with your dad. You should fix the issue by talking to him and then you can go back to spending time with him.