About feeling a bit miffed that I have to buy presents for my half siblings

[Azquilith]

So, my parents have been divorced forever. Both remarried and with 8 children now between them, I am the eldest.
My one full brother and I used to split time equally between parents. When my Dad remarried when I was 15 he cut that contact as his new wife wanted him to move to a new house with no 'history' (basically us) and start a family. Initially we had a room in the new house, then no overnights and a 'space' then barely any contact, and all outside the house. Once I left home contact with my Dad improved but we'd meet at his parents who live nearby.
When I had my first baby last year, I asked if I could come and stay with him to show off my baby. He has a spare room and two kids with wife. He said no. Turns out that wife now won't have me in the house, or my son. Won't speak to us or acknowledge us. I still occasionally see her children (8 and 10) when my Dad brings them round to his parents but it is difficult to form a bond when their mother is openly (as my Dad has admitted) unpleasant about me.
I forgot that it was my half brother's birthday last week. I now feel insanely guilty and will of course send a present.
But I can't help feeling aggrieved that she can slag me off, not see me, not have me in her house, but I'm still expected to be the bigger person with her kids.
FYI, I have never done anything to install this unpleasantness - years ago she told me at a party for their friends that she hadn't told anyone my Dad was married before and so they wouldn't know who I was, and could I not say. Now she just finds it easier to physically cut me out. She's just weird.

She's a dreadful person. Are your half-siblings nice?

Well I find them a bit spoilt to be honest. Lives are run completely around them and their activities and they are very spoilt. I also find them a bit rude. But they're kids so I try not to judge.

They are not just her kids though are they? They are your dad's too. Your family. Don't let her unreasonableness destroy that relationship.

Your poor dad. How dreadful to have his wife behave that way. But why does he let her?

Your dad's wife sound horrible
I'd send a board game addressed to whole family and be done with it.

i tell you something I'm a step mother too and back in past when my step children lived with us we not alwasy got on. But i knew who I was marrying and yes soemtimes Id say something on them to my husband, as I always thought i was this outsider who could give him an honest opinion about his children. Now I have children with my husband but no matter what was relationship between me and my step children they were alwasy welcoem to come and see their dad, if I didnt want to see them Id go and spend time with my friends or so on but Id never tell them or even my husband not to welcoem them here. Another thing is even if I did my husband would never tell them that I had said something rude about them...your step mpther is an adult and so are you, Id insist your father stood up to her and tell her you were his child before she was his wife and as life shows already she isnt the first or only one...

and as about the siblings, my children love their bigger sisters and Ive to say i did find it hard sometimes but it is actually lovely seeing my hubby with all his children together. I never exoect presents from them for the children, so no you dont have to buy them anything maybe suggest why cant you all go for a meal as thats what we do to celebrate birthday here.

better I yearn for a stepmother who would at least have us in her house. We live 200 miles away so I wouldn't be a frequent visitor, I appreciate that it's difficult with split families. My DP has two kids himself from a precious marriage.
My Dad disappoints me because he puts up with it. Basically he was desperate to find someone after years of being alone. So he went along with it until he realised how unreasonable she was and by that point they had the kids and I don't think he could bear having another broken family. So he chose them over us.
I kind of deal with it, but when it gets to the point when my son can never go to Grandad's house, I'm not sure what I'll do.

What an utter cow! As a proud step mum to a 12 year old boy I am horrified by the idea that he wouldn't have his room at home at any age.

I think you are far too nice. If you feel you must send presents, why not send ones with 'FROM MY LOVELY HALF SISTER' on them in big letters? Or a nice copy of Cinderella or Snow White? And you should deffo look into inviting your Dad (although he too is a waste of space) and your half-siblings to stay with you - obviously on the invite you need to write that you haven't included step mummy as you know she wouldn't want to come and you don't want to make her feel threatened, poor dear.

Your dad should have grown a pair years ago! He is just as despicable as she is for allowing her to treat you like that! I think I would be inclined to think stuff it, and not bother at all in the future. You don't need people like this in your life - dad or not!

She is a disgusting woman and your dad is horrible for putting that witch above his own flesh and blood. I would disown your father as he has not been a good dad to you.

Don't blame the children for the sins of the parents. You need to separate the awful behaviour of your father and his wife from the two innocent children in the middle of this. There may come a time in the future when they are grown and will want to have a relationship with you as adults and taking a few small steps now to maintain the relationship between you, even if strained due to their parents, may make the difference.