Ok so a bit of backstory: DH and I have been together for 20 yrs and have DD16 and DS14. Then there is SD30 and SD28. Last time I saw OSD was 12 yrs ago when I had finally had enough of her spiteful and entitled behaviour, told DH she was no longer welcome in our house and disengaged.

As far as OSD is concerned, DH is a Disney dad and she can do no wrong. BM does not parent either; she is their 'friend'. An alcoholic can't-be-arsed-to-work friend - but a friend nonetheless. Last time DH saw BM was in court 8yrs ago when he finally managed to get spousal maintenance overturned. BM has not enjoyed life since the gravy train of spousal/child maintenance stopped. She is still single, still drinking and still blaming OH (and me) for ruining her life. She did a very good job of PASing the SDs. After years of being told that BM might be dead/not there when she got back, YSD chose to stop visiting us and more or less cut herself out of our lives completely. DH does try to maintain contact but it's very rare she will respond to calls.

And now OSD is getting married. DH chose not to tell me this; the first I knew of it was when an invitation arrived with all 4 of our names on the envelope - but no names on the invitation itself! I was amazed that DD, DS and myself had  even been invited but DH sheepishly admitted that he might have told OSD that 'it would make it awkward for him' if we weren't included. I just wish he had phrased it differently ie if you disrespect the rest of my family by not inviting them, I will not be attending.'

OSD is very much the mini-wife and did not want me in their lives, let alone the arrival of DD and DS. Obviously she tells it differently to DH, who is so desperate to believe that one day we're all going to be one big happy family, he will believe anything she says. Actually he believes eveything that comes out of her mouth because 'she does not lie'.

Much as I do not want to, I have agreed to go to this wedding. BM has an evil tongue (and daughter's wedding or not, is quite likely to use it).  She has never met DD or DS and I do not trust  DH to have their backs, or even notice it happening if she starts. I'm not prepared to throw them to the wolves so therefore I am attending.

DH does not get that OSD uses him when it suits and withdraws when she does not get her own way. I have  a  feeling that she did not expect us to accept the invitation as  a family, and I wonder what punishment will ensue as a result. DH tells OSD what she wants to hear and it also transpires that DH has discussed things with SD which he had no place to do so. I doubt I will ever fully get to the bottom of this but the knowledge that it has happened is making me feel very much at a disadvantage.

My anxiety levels are through the roof. Nobody on DH's side of the family has been invited until the evening reception so we have around 6hrs sat in a room with BM's family and cronies before anyone we know arrives. 

Just feeling in need of  some support right now.