Bright, Calm down! Breathe! You've worked yourself up into a frenzy and it's not worth it, especially over a Christmas card and newsletter from his family.
Many families send out newsy letters w/their Christmas cards. My mother gets one every year from her god child and it contains so much info about her family, what they've done, who got married, died and divorced. It's only a way of letting people know what's happened and nothing more. Yes, it can be taken as self absorbed or, as I put it, bragging. But it's their way of keeping people abreast once a year. Nothing more. Let the emotions over this letter go. It's not worth spinning yourself up. Let it go!
I can sense that you are very close to exploding. Your emotions have been bubbling since that wedding and I'm sensing that each and every action that is coming your way, you are getting more and more annoyed/angry about this stuff, i.e., the mail, his being in your town, the friends at the vacation place, the non-invite to the wedding, him dropping by, the redecorating of the vacation home and FB. All of this stuff has really been getting to you.
You only have control over what you do and how you react to things. If the mail is bugging you, you know what to do about it. If the friends are friendly w/the both of you, then you will need to find a way to remain friends w/them, or just drop them. If you opt to remain friends, then don't discuss your situation w/them. You are the only one that can decide whether or not to have him come by your place and if you prefer him not to come when you aren't home, then you need to set your boundary and tell him. As for the in-laws sending you cards and news letters, either don't open them up or read them and let the information go. (Yes, it's difficult, but you can do it.)
You need to find a way to detach from this stuff. The anger and anxiety that you have is going to start affecting your health. Find a way to release the emotions and try to look at all of these actions as nothing personal against you. Don't sweat the small stuff and you do have the power to change things that are within your control...you will know when you've had enough and will begin to change things so that you are in a better place.
I am very sorry that you are spinning like a top right now and hope that you'll feel better soon.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.