Hi @Justaguy1 didn't want to just read and pass on by. You sound lovely.
How old is the child you are saving for a house for? I wasn't sure if it was a house for your ex and the child, or a future house for the child alone when grown up? Either way it sounds like they are safely housed now and she has a new partner?
I think its really laudable that you are showing you love all your children equally. But saving for a house is a long old haul, and a major expense quite apart from how your ex is using the money for other things. I think looking after yourself too - going out enough, having the heating on, little treats - matters.
I don't think anyone can expect to get a house wholly bought them by their ex/their father without their own input too, certainly not if it isn't funded from say previous shared home. Are you paying maintenance for the other child? Do you think this is what your ex is using the money for? It might be clear in your mind it was for a house for the child, but in her mind it is you contributing to the child's upkeep? But personally I wouldn't be contributing to a savings account for a house, which was what we'd both agreed it was to go to, if the money kept disappearing for other things. If you want to keep doing this, could you maybe have a bank account you keep control of for the child, or put it in premium bonds in their name which you keep control of?
I'm a single mum of now young adult children. I'm paying for other stuff for them (university maintenance, food etc for the one who is with me now) but not saving for a house deposit for either of them. Can't afford it and other things come first. Of course if the boiler doesn't go etc I hope I'll be able to help out when the time comes. But I'm choosing to prioritise some heating, some camping holidays, some takeaways etc now. There will be ways to show you still care, and to continue to be that reliable father figure, which are smaller scale than a house. That isn't to put you off it, but just to say it sounds a major undertaking, and particularly with your ex's history with debt, and maybe something smaller, and in your control, might be a more manageable first step?