My ex left before Christmas. I've said I would pay mortgage for now in full as he left. He just needs to ring lender and authorise it. We have 50 50 share. He won't let me. So I said I would pay my half. He won't ring and authorise it. He wants me to put it in into his bank. He's already threatened to stop paying it twice. I am right in thinking I don't have to put it into his bank aren't I?