Hi fth, Do yourself a favor and take what you can while he is feeling "generous". In many, many cases (including my own) the WAS is much more generous at the start of the process and as time goes on, becomes much less so and starts to feel "entitled" and that they owe you nothing since you are cause for all that is bad in their life. I've seen it happen to me and to many others here on the forum.
Don't worry about him seeing how he is sticking you with so much responsibility and work for the kids. It won't make one bit of difference to him at all. You need to understand that to him YOU are the "bad guy", the one who "messed up". He is just doing what he MUST do because of all the bad YOU have caused him in his life. He needs to blame you for his actions because if you aren't the reason, that only leaves him throwing away his family for a woman much younger than him and what does that make him? I have a feeling that he has been doing a lot of traveling with OW and spending of money on her and he wants to hide that, that is why he doesn't want you seeing "his" accounts (PA and CA are community property states and they are as much YOUR accounts as they are his and the business is as much yours as his. My W lost sight of this as well). There is no way he won't have to disclose the amount of funds in ALL the accounts as it's half yours until you say it's not and a judge signs off on that.
It is a very good offer but also keep in mind that he is an adulterer and you have been married 19 years. The courts in PA WILL take this into account. Not to mention the fact that if it goes to court the world will know that they (good Christians that they say they are) were committing a heinous sin against you and God...and MLCers HATE looking bad. Heck, he can't even face the family for a kids party when they don't even know about his young chickie yet!
As for the "talk" with the kids...my W STILL hasn't had an honest talk with our girls! She actually believed that they thought the reason she was sleeping on the couch was because I snored too loudly! Remember, their empathy chip isn't working at all and that includes the kids as well. My W went from being a stay at home mom for 15 years to not caring or denying that D hurts the kids. According to her D doesn't have any adverse effects on anyone as long as we both "act right" during and after. Never mind the pain she went through when her parents D's or every expert saying how bad it is...only OTHER peoples kids are hurt by D. In fact she actually thought (and may still) that they would be 'happy" that their mother will finally get what she wants and be "happy". In fact she said she will be a better mother because she will be so happy just because we are no longer M. MLCers don't think like normal people, remember don't believe anything they say and half of what you see!
It's good that you are doing this now and getting everything prepared. I will say that you definitely need a lawyer. Your H isn't going to stop until he gets what he thinks he wants so badly and he isn't going to allow himself to stop. This is why he doesn't want to see you or do things as a family..not because it hurts too much but because he doesn't want to allow himself to waver. My W did the same type of things...she got angry when we did things as a family and had fun. The only times we really fought when she was still at home after B-day was after we had done something really fun as a family and she had a good time. It scared her that she might start to think she didn't want a D and she had made up her mind. Hang in there fth and try to keep a cool head. Remember, the man your H was is no longer there. You aren't dealing with the old H and you need to keep this in mind at all times.