I have a 4 month old, and on Christmas Day both he and I fell asleep in the Play Room at my in-laws' house, and missed dinner (well, obviously he wasn't having dinner!). I slept for 3 hours, missed dinner and the clear-up, and felt a bit bad. But once I got a bit more sleep and talked to DH, I realised nobody minded!
Yesterday DS screamed from about 3pm onwards. I don't think he hates me; I think he's teething and tired of all the fuss and fed up being dragged in and out of cars... And that's ok! As far as he's concerned, it's not Christmas, it's not a special day, and all this bother is really a bit of an annoyance.
You sound lovely, but tired. Can you take a few days with DH and baby, just stay at home, snuggle, and take it easy? You will get through this - the newborn phase passes, like all others. Give baby the gift of a well-rested (or vaguely rested; let's not be too ambitious!) Mummy and lots of cuddles, and it will be the best Christmas ever!
I agree with those say you should see your doctor and tell your mum. I've had depression for years, but it never feels like depression; it feels like failure. The first time I went to my GP and blurted it all out, and she then just took a deep breath said "ok", it was such a relief.
BTW, if you're worried about medication while breastfeeding, don't be - there are options.