My husband and I have two bio kids (5 and 3). His 11 year old son from his ex has already been on two holidays this year with his mum. We’re going to Cornwall next month and I’ve said I only want to take our two. I pay half and I want family time just us four. It’s only fair he already gets extra holidays with his real mum while our kids don’t. My husband is furious and says I’m punishing his son. I don't have anything against my stepson and it's not about not wanting to spend time with him, but my kids are noticeably angry they get less holidays and I need to make it fair to prevent disputes. I need to make my intention VERY CLEAR. AIBU?