How do I, a person who deals with being excited and anxious by getting overwhelmed, teach my kid how to deal with being excited and anxious in a different way? I have no idea.

The other parent isn't helpful (doesn't get excited and anxious in this way).

#ActuallyAutistic

@quidcumque It entirely depends on what you want to teach your child. What does it mean to be "excited and anxious in a different way"? Why different?
This question isn't about parenting methods. This question is about what you hold valuable enough to be taught to others. And in this case I think that value is more about your own (in)capabilities. So talk about that. Talk about you. Ask you child for help.
@KoosPol I wrote "DEAL with being excited" and I did mean exactly that. You can deal by yelling and hurting your siblings, but I guess there might be other ways.
@quidcumque Ah, thanks, gotcha, it got lost in translation.