I'm going to hard ghost my (twice) ex out of what probably seemed like nowhere
Why would you ghost your ex?
Because our relationship went to shit.
It sounds like you two should stop seeing each other so you don't get back together yet again. But ghosting someone you've dated in the past is rude.
Who says dating someone twice means we're in a relationship.
Well even if you aren't still in a relationship with this person, it's wrong to ghost anyone.