I'll try to reply to as many points as I can. Apologies for any I have unintentionally missed.
@tiddlypops
I've arranged a solicitor meeting next week to get the divorce wheels in motion. I don't think she likes been here anymore if I'm honest as she is sleeping on sofa, I ignore her and even kids ignore her (not thru anything I've said or done - I'd never manipulate them against her as she is still their mum). However, this evening after been ignored again, she just looked genuinely sad and I felt myself feeling sorry for her. It didn't last long as legal threats against me started again re. Disney trip before she left to go out to her dad's.
@decormad38
I know very little about the toyboy other than he dumped his girlfriend and 4 year old recently. He is around 10 years younger than my wife and they work in same office. Other than that i have no idea what he looks like or anything and to be honest i dont want to know! In terms of contraception, my wife gave up the pill due to worries about hormones/cancer that she read online (She is a real hypochondriac and has had numerous "health scares" after reading things online). We relied on the withdrawal method as she didn't like condoms, but she hasnt really been interested in sex since having our 5 year old, stating there's no point in it. Ive said to her that toyboy will expect her to up her game but she just said I don't know what I'm talking about.
@justlikedevon
How awful for you. That is terrible and I couldn't stand for that. I'd have to at least throw cold water over them! I'm slowly realising she is no longer my friend, it's just so hard to accept that your best friend for 20 years can just turn on you in the most painful way.
@sausagerollers
I'm scared of telling kids and I don't know what to tell them if I'm honest. It's also going to kill me to lose my 5 year old for half of the week as we are inseparable. I know some may say that's not healthy or normal, but I've had to bring her up a lot of the time by myself due to wife working or going out. I've forgone work/social life as she is a little miracle as we were told we could never have another child after our oldest (She is definately mine as she is spitting image of oldest and similar features to me when I was young... no need for paternity test! Lol).
@stormy76
Yes I think you are right as they tend to disappear upstairs when wife due home. I just don't know how to broach it.
I have been doing housework for months so the house is in a good state and the kids are well fed and know I'm there for them whatever they need. I've done an online check and can afford to remortgage and get "what she is owed" but my solicitor warned against any settlements until everything done and agreed legally.
I'm pretty certain the "love" for toyboy will not last as I'm not sure he understands what a complex person she is. Also working and living with someone can, I imagine, mean you feel completely smothered by each other. I've told wife to never post anything on social media with toyboy as our oldest follows her and would devastate them to see their mother acting this way.
@theredbarrows
Not sure what amendment exactly. I think she wants me to amend the dates as I have a feeling she's organised something for bank holiday weekend and wants kids with her. Other than that i can't see anything other than spitefulness.
@nagsnovaballs
Yes, I've used this advice this evening. Told her that I'm not changing anything and I'm planning on going. I told her that if she still refuses then it's up to her to tell kids that their mum won't let them go. I'm hesitant about telling kids about toyboy as I don't want them getting more hurt than they need to be.
I have a lot of family nearby so will be able to rely on them when it all comes out. We are not a close touchy feely family but support each other when needed so that dies offer comfort.
@64632k
I honestly don't know what went on at the party when her drink was spiked. I know she has lied about a lot but I do believe it was spiked as others at the party had similar experiences. I do have concerns as the hosts are known for their free love antics but again, will likely never know...it's just part of her spiralling downwards and off the rails.
@nyushka1
Thank you. I've asked myself what I did wrong to deserve this. To be fair she has said it's nothing I've done, but it does make you doubt yourself: am I ugly? Am I worthless? Why me? I've thought it all, but I'm slowly realising I'm just a passenger in her disastrous life choices. It's difficult to get over the feeling of ugliness and self loathing but I'm getting there. A random thing helped the other day. I was at Pret buying a sandwich and choc bar. The guy serving me said the choc was on him. I thought it was odd but after googling found out it's policy that staff can give out freebies to those they find attractive! Lol Its not necessarily the type id like to attract but I can't be that bad looking if a young guy at Pret fancies me! Haha I could have had my own toyboy! 
@princesstiggerlily
The reason kids may not know, is that this has been "normal" in some way for almost 6 months. I'm not angry in front of them and they are loved and cared for by me. As I've said above, I'm scared of telling them but know I need to get a backbone and let them know.
@windygate
Thanks, yes I'm pulling stuff together and getting things lined up. With regards to her father, I think he has agreed to pay her legal fees so am expecting a potential fight. I'm hopeful it won't come to this but I have to be ready.
@wallywobbles
Again, thanks for comments. I'm hopeful of getting the ball rolling next week.
I'll keep this thread updated as ive found the others on mums net really useful. If someone in the future needs advice this forum is invaluable.