So a bit of background.
DP and I have been together for 8 years and have been through quite a lot of significant life events together although we do not live live together. We both have children from a previous relationship. His children sadly do not have a mother in their life and my child does not have a father in his. My son was only a baby when we got together and calls my DP Dad, his mother Grandma and his brother Uncle. The children generally refer to each other as siblings. I have always been quite involved with his children and used to take them to school and pick them up when needed, attend parents evenings and have even gone alone to their school assemblys and sports days when my DP hasn't been able to attend.
DP has a family member who is getting married soon and DP's children are set to be rather involved in the big day.
The issue is that my son & I have not been invited to the wedding (but have been invited to the evening do). This in itself is not an issue, I am fully aware they are entiltled to invite who they like etc. and generally I would be fine with that. The thing that has really pissed me off is that whilst I am not invited they have invited BIL and his DP of 2 years when the only time they ever have anything to do with anyone in the family is when they're broke and after money.
I work weekends and had I been invited would have booked the whole weekend off so that we could have attended (and left) as a family. Since we would have been attending together we would have split the cost of sharing a cab and with having no work the following day I could have had a drink. However I am now basically expected to work all day, go collect my son from childcare, rush home to get us both ready, drive to where ever the venue is, have to go find my DP (who by the time the evening do starts will probably already be half cut), not be able to have a drink because I have to both drive and get up for work and have to stay for more than 2 hours (do starts at 7.30) to not be seen as being rude and antisocial and then go home alone.
So the crux of the matter is, AIBU to not go as quite frankly it is too much like hassle when I'm neither being invited as part of the family nor am I a friend of the couple who's wedding it is? Does that make me a total bitch? My DP seems to think that I am.