Can my degree be revoked if my relationship with my advisor sours post-defense?
Once a degree has been conferred, it is exceedingly difficult to retract at without clear evidence of misconduct. Having a souring of relations with your advisor definitely does not rise to the level where you should have to worry about your degree being revoked. It is definitely worth mending your relationship with your former advisor just on professional grounds, but the "safety" of your degree shouldn't be one of them.