I'm sorry to hear he changed his mind last minute and cost you a lot of money that could of been used for your family. Have you thought about
"no contact" to stop the bleeding, giving space for you to heal and focus the energy on you and your family, and get him out of your daily life activities?
You replied while I was modifiying my post. Sorry. I think that you have a couple of options... .
a) You could say nothing and go no contact.
b) You could say something like
"I'm sorry friendship is out of the question. Good luck on house hunting" Keep in mind that he may try to get you to reason with him with why you changed your mind. To stop
his drama I recommend to not JADE ( Justify, Attack, Defend or Explain) the reason why you changed your mind, you have that right to change your mind. Say things once and let your words stand.
"No Contact" the Right Way and the Wrong Way"No Contact" is mostly about the non-borderline forcing "distance" into the relationship to help the non-borderline heal; to get the "space" needed to get over the hurt; get on with their lives.
The key elements of "No Contact" are
~ to get the partner out of your day-to- day life,
~ to stop thinking in terms of a relationship,
~ to take them out of your vision of the future,
~ to stop wondering about how they are perceiving everything you are doing, and
~ to stop obsessing with how they are reacting (or not reacting) or what they are doing.
These are the simple objectives of "No Contact". You may need to remind yourself every day of what you are trying to do. It takes focus and determination to do this - at a time when you probably just want to sit down and cry. Just keep reminding yourself that it takes great strength and determination to be emotionally healthy.