I don't think it is possible to get her to think sensibly about this or much else. You may have learned your way out of emotional decision making but your mum hasn't and more than likely never will.

I do think you might need to reconsider purchasing a house with your mother given this kind of a divide between you. Who you are now, and who your mother is now, how you both individually and collectively make decisions now isn't going to change much. The conflicting 'styles' is not going to change.

It reminds me of the old story..... 'I thought if we got married things would be different.... I thought I could change him..... I thought.....' Well..... we know where 'thought' can take us if we aren't careful.

So ya.... you have to shut up and stiffle and let her do what she is going to do. The question is can you do that? Can you live with the affects on you? Can you do it without causing you harm? or her harm? Can you shut up and accept her ways or is it going to be something you have to stuff and stuff until you explode?

This could well be a wake up call for you to think hard if this plan is actually going to be able to work. However this unfolds I pray nothing comes in the way of your relationship with your mother.

Blessings