Oh love. He's 12 weeks old. He will not, I promise, remember this, or most likely next Christmas. So firstly, put that particular worry that you have ruined his Christmas right out of your head. Secondly, you have just grown, given birth to, and are learning to look after a totally, brand new, gorgeous, amazing, but utterly selfish person. You are very entitled to feel a bit all over the shop. I did. Twice, and I will be amazed and slightly worried if I don't feel the same this time. I read once, and I'm sure someone else has already said this, that if an adult treated you in the same way as a newborn does, they would be arrested, prosecuted under the Geneva convention or you would give them a slap. So it is totally fine to feel tired and a bit pissed off right now and not feel like Mrs Claus.
Thirdly, and most importantly, if you are having negative feelings about yourself and your place and use to your baby, please talk to someone in RL. Doctors are trained to recognise these types of feelings, as are HVs and Midwives, they will not judge you and neither will your family. If you can, write out bullet points of how you feel to take to an appointment, so that you say exactly how you feel. Take every offer of baby minding you are given, so that you can wash, eat, sleep and go out for some fresh air on your own, even if it's only 'round the block. Makes a massive difference.
Keep MNing too, sometimes just sending your feelings out there can work wonders. Anyway for now have 
and 
on me.