Advice on not losing my cool

[devastatedbuthopeful]

Can anyone suggest ways to stop me losing it when my H arrives here tonight to discuss our separation?
Brief synopsis - H left me in October after 21years, I found out he had been having an affair for the last 3 years and he moved in with OW straight away. He claims they are in love and he wants to be with her. OK, he doesn't want me but he claims he still loves me and wants to look after me and provide for me and DC as he has always done.
I last saw him 2 weeks ago for the same discussion and I just ended up crying the whole time. I try to keep a lid on the anger as he says that if I shout at him he will leave but I cannot help the tears.
We need to discuss things I have a solicitors appointment in the morning, he hasn't appointed one yet despite me asking him to. We need to get this sorted, I cannot trust him anymore nor OW. I feel very vulnerable.
But how do we do this, I need to keep him onside?

Can you go for a short walk now before he gets home? To calm yourself down and clear your mind.

Can you not think of something to treat yourself with after he has gone, that will keep you from loosing it? maybe something you could not have done if he were still there?

Thanks for the suggestions. I might go to the gym for a run or walk the dogs.
I just get really overwhelmed by him and the situation he has put me in, through no fault of my own.

Why dont you treat it as a business meeting. Write down a list of things that you wish to discuss. He has said that he wants to provide for you so write down what you expect, ie financial contribution, mortgage, bills, access to the children, holidays, school trips, uniform etc. That might help you to be less emotional. He has already said he is staying with the OW so there doesnt seem to be much point raking over emotional territory. If you have an agenda, it might help you to stay focused so that you can see a way forward.

Yes that is what I did last time and I still have the list so I might just re-use it.
It's hard to stick to it when he is so reasonable, I just get caught up in my feelings for him, which I know are pointless and I'm just hurting myself, but I can't away from them.