My 2 female cats who used to get along GREAT dont anymore.?

I have a 2 year old cat and a 7 month old Kitten. Both are females. They got along fantastically for the first few months. Always following each other around and snuggling and purring. They were so happy. We just moved to a new flat about 3 weeks ago and things haven't been going so well. At first they were fine and happy. but the 2 year old is getting really aggressive with the kitten. The kitten walks up to her and the adult cat hisses at her and smacks her for no reason. Now the kitten is half afraid of her and desperately seeking love and affection from us at night...but then the adult cat gets jealous when she sees the kitten with us...This has all happened over the course of the week. Now they are both getting spayed next week. The oldest one has been in heat around the kitten and has been fine in the past. But I guess i'm just wondering if when they both get spayed and settle down in the new flat if the aggression with stop, and will they be happy again. I feel so bad for the kitten right now, she looks so upset all of the time. And I feel so badly for the adult because she seems so jealous. I dont know what to do!