Butterfly ofcourse you don't wish to cause a scene for this poor girl, as this is her special day and even more so considering the really tragic circumstances of her situation. However it wouldnt be YOU causing the scene, that would be sd. You yourself stated that sd cannot behave around you!

This invite included you? You are SO partner and had arranged to already attend with him as such? So who the F*ck gave him the right to throw you over because little miss snooty pants decided to pull a power play, which btw worked?

Perhaps sd genuinely wants to attend this wedding because of her link with this girl and again considering the sad circumstances, BUT if she cannot behave herself then she foregoes the right to "insist" she attends. No one forces her to behave nastily towards you, she chooses that all by herself, aided and abetted by SO. You do realise don't you that nothing will EVER change because your SO enables her? Plus by you accepting the fact that SO treats you in this manner you in also enabling him to continue enabling sd?

I can see what a horrible situation you are in, its exhausting and its hurtful, not only to be disliked by sd by to be shoved aside by SO when he can't be bothered to address his DD's attitude problem with you. Parents need to realise that giving their kids what they need, not what they WANT, IS an expression of the deepest love possible because its selfless. Its easy for SO to take the less problematic option, he will justify till the cows come home...shes just a kid...its easier this way...you didnt really want to go...

You hear this often enough on this forum, that many of our men needs to take back their mangina's from their ex's and kids, however in this case I genuinely think YOU need to consider if this how you are prepared to be treated for the rest of your life? You have every right to be considered and you need to stand up for yourself, because no other sod will. The best way to get this message across is to quit putting up with crap quietly. If SO is out of order, then quietly, calmly make him feel as small as he is acting. Realise you should not be shielding shit like this from his family/friends, so if you want to go to the wedding then go, but go by yourself or with friends. DO not sit near, make eye contact or engage with anything to do with SO and his children-you should not have to miss out because of miscreant. If you feel you cant do this, then go when you know they arent around, or alternatively go out with your friends and go ALL weekend. Not for revenge, but I wouldnt want to even see my SO after that. I would get some physical and emotional space to consider my options, plan and make some decisions. Having been there, I know I came to a point where I realised that no matter how much I sacrificed it would never end, be good enough as someone would always be attacking me from OH's side of the family/his ex/his kid. So I started to put me first without a bit of remorse, I knocked some sense into me as I realised that was exactly what my SO had been doing all along. Prioritising everyone except me. So if the shoes fits, then I was going to have a go, as I if things were going to fall apart then it would be on my terms.

p.s. Got to say you know its NOT okay, for SM's/SF's to be used and abused all because there are "children" involved. Their happiness and welfare does not negate everyone elses, that is a warped and unhealthy view. If a parent believes this, then I would say do the dating population a favour and stay single. You are entitled to think this way, even though personally I think its damaging for children to be brought up in an environment with no consequences, no consideration or thought for anyone else, but its horrendous when innocent bystanders get dragged unwillingly into that. JIMPO.