I would call him out. I would start slow, and escalate each and every time he does this. This behavior likely did not start recently, and it will doubtless continue UNLESS you teach him to treat you differently. You do not have to be damaging or hostile, but you do need to be firm. Changing this dynamic is going to take courage and discipline on your part.
You could begin with questions: Are you aware that this is difficult for me? Why, exactly, are you pointing out what might happen to me, such as the need to downsize? What is your point? If the shoe was on the other foot, would you expect this kind of comment from me? Where do you get off, treating me this way?
That will rock him back on his heels.
You could also begin by just saying, "gee, that's a douche-bag thing to say." I'd expect better from you.
My feeling is that we only get one family. The decision to continue/not continue this relationship is a far reaching one -- one that you may regret. Siblings are the only people who know us most of our life span. I would go slowly here. Crappy co-workers in dumb jobs are one thing, family is another matter entirely.
(You can see my post about a co-worker who has repeatedly been disrespectful of me due to my weight loss. I called her out, and the more I think about this, the better I feel. I should have done it much SOONER. I regret eating her shyte sandwiches, week after week. Sometimes you just have to change the terms of the deal.)
