Background:
I was a nanny for one family for a long time, 12 years. I started when the oldest was 10 months old and finally left when she graduated 8th grade. I was there everyday, many weekends, traveled with them, you get the picture. I was very involved and engaged with both kids and love them very much.
After I stopped taking care of them daily, I still kept in touch. Emailed all through college, they were both in my wedding, girl house sat for us, got together when possible, etc. This relationship went both ways, I got long detailed emails from both kids, gossip about kids they grew up with, moans about classes, talk about boyfriends and the like. I would say our relationship was about the level of a fond aunt.
A few years ago, she met "The ONE" and they have been blissfully happy ever since. He proposed last year and the planning began. We talked about her bridesmaids, she sent me pics of her wedding dress and details about venue, wedding planner and so on.
The wedding is this Sat. About 6 weeks or so ago, I realized I hadn't received an invitation. This is a fairly large wedding with guests coming to the area of the wedding from across the country and overseas so I knew the invitations would have to go out pretty early. So I waited and waited and...you get the idea, and no invitation ever came.
To say that my heart is broken and I am sad is an understatement. All the excuses one could give do not apply. Venue is large, family very wealthy so space and money not an issue. The truth is she simply didn't invite me. Just to make sure there wasn't a misunderstanding about the invitation, about four weeks ago, I sent a FB message, just saying I am so excited for her and thinking about her and her DF, nothing about being invited of course. I thought that if she had invited me she would say something like "see you there" but nope.
So Sat she will get married and I won't get to see her walk down the aisle as I always envisioned. I will send a wedding gift and a nice heartfelt card but I will always have a pang thinking about it.
Thanks for reading (if you still are!) it helps to get it off my chest.
OMG! This brings back so many memories of my own wedding.
First of all, let me just say how sorry you are that you are so hurt.
Just wanted to mention my own experience and how maybe you shouldn't take it so personally just because it is such a BIG wedding.
I had 600 people at my wedding. Yes, 600! And to this day there are people that were upset with MY parents that they weren't invited to my wedding that happened over 14 years ago.

And I also had guilt over who my DH and I couldn't invite.
Both DH & I grew up in a HUGE multi-generational church that my parents still attend. DH's family went on to help start up a branch church. DH's family also had a large business where they treated the employees like family. My parents both had LARGE families that all lived in the area. Starting to get the picture?
When we first got engaged, we went with the parents (about a year in advance) to book the banquet hall. 600 people at 60 tables should be more than enough, no? 200 for DH's parents, 200 for my parents, and 200 for our friends.
I didn't have to work on the guest list for DH's parents but I'm sure they had to cut people from their list. My parents sure did. They had to include family which was already around 100. Then there 2 tables for just the pastoral staff of our church and other clergy they were close to. Then we had a large church congregation to invite. They had to cut everyone that they hadn't seen in a while (former employees, nannies, family friends) who were a bit hurt when they found out later on that I had gotten married and they hadn't been invited to my parents' one and only daughter's wedding.
When we found out that we didn't have enough room, we went back to the banquet hall to add tables. Unfortunately, they had booked another gathering in the smaller adjoining room so we couldn't add any more tables or people.
DH & I had to cut down our list too. We had to exclude ALL significant others unless they were married or engaged. We had to include some co-workers. We limited the amount of personal friends we could invite and if they were mutual friends, we set some cut off at like we had to have known them for at least 3 years.
For example, there is one family at church where my parents have known them for decades. The parents of the family were included in my parents' guest list. They had 3 sons, one was DH's age and one was mine and they had an older brother who was a few years older and was married with a baby. We grew up with the 2 younger brothers and both knew them. I knew the older brother slightly and had been invited to his wife's baby shower etc. but DH did not know them at all. They were older and he never had any interaction with them. We had to cut the older brother and wife from the guest list. To this DAY, the Mom in the family still holds a grudge against my Mom (she sees her every week at church) that her ENTIRE family wasn't invited to my wedding.
We also had to not invite a girl that we had only known one year and not that well. Our cut off Problem was that she was roommates with another girl that we had known YEARS and HAD invited and had started dating another person also invited and we were all in the same "youth group."

It was awkward and probably hurtful to her. She later married this friend and still gives me the cold shoulder. But we had made the cut off 3+ years or EXTREMELY close and she was neither.
We should have just eloped or kept it REALLY small. But when someone thinks that it was a HUGE wedding and it WAS and they seemed to be the only one NOT invited there tends to be a lot of hurt feelings. Wished we could have invited EVERYONE but we had to cut over 100 people just to keep it in the 400 that was allotted to us and my parents.