OP despite the fact I think your kids are being selfish gits, as a mum I would not want to lose anything from my kids because of an ex husband and his new wife. Is the new wife the 'Other women' or did he simply meet her after he left you?
If the latter than I would not feel quite so cross towards her. Either way, he let you down, I would try and quell the anger you may feel for his wife.
In time, I really hope, you will find peace and feel able to accept how things have worked out. I say this only because I think that, in the end, coming to terms with this will be better for you.
If I wanted to be charitable to your children, I would say that I think maybe they have this in mind. Or at least maybe some of them do.
I would maybe (in your shoes) talk to them, ask them why they want everyone to 'get on and be a family' and also maybe ask them how they think you can do this. The ex and his wife are not your family but you 'share' family so I can see that being able to be in the same room may make life easier for all of them, including you.
This may mean that you are able to fully participate in the lives of your children. If you are the one saying you cannot be where he or she are, then you may be excluded from some things.
This will not help you and in an awful way will give your ex and this woman a further 'victory' over you. Please find a way to move forward towards a time when you can be in the same room.
Counselling may help, as may moving on with your life and rebuilding it, doing what you want to do. Even if you do it with the express desire to show your ex how happy you can be without him, whatever your motivation, please find the way to move forward for you.
In your shoes I''d get some really good things going in your life, start writing a book, or take up a new hobby, book a fabulous holiday (if you can afford it), look brilliant etc and when you are around him just talk about the new you, who is doing new things, nothing to do with the old life.
That's what I hope I would try and do, for my own peace of mind. But how you choose to proceed is totally up to you, not up to your kids. 