I think you handled your mothers problem very appropriately, offering her the support that most people needed to hear. your mother is the one being selfish. it sounds like that she is angry at you and this is coming out in unpredictable ways. I don't think you will ever be able to share your happiness with her because she is not ok with you right now. I would not ever expect her to be supportive of you or you will just be let down. having superficial conversations is the only safe way to maintain the relationship. if you want more than that, you can suggest family counseling for the two of you to work out what is going on. I am sorry your mother isn't there to share your happiness. merry Christmas to you too.