Should I Pay for My Ex's Kid to Come on Our Disney Trip?

Divorce can be messy, especially when there are kids involved. But what happens when you're planning a special trip for your own child and your ex's kid wants to come along? This is the dilemma one Reddit user is facing. After a difficult divorce due to infidelity, the user's ex-husband had a child with his affair partner who has since left him to be a single dad. The user's son sometimes spends time with his half-sibling, but now that they're planning a Disney trip, the ex-husband is insisting that his son be allowed to come along, too. The user is hesitant, as it would mean paying for another plane ticket and supplies. The ex-husband and some friends are calling the user selfish and petty for not including the half-sibling, but is that really fair? What do you think? Let's dive into the comments and reactions to see what others have to say.