Please talk to your friends and relatives who have gotten divorced and get recommendations about their attorneys, which ones were great, which ones weren't great. Call the women's domestic violence or homeless shelters for recommendations. You might get lucky and find an online support group of people who have gotten divorced in your state/county who know who's a pitbull (good) and who's not.
But whatever you do, get an attorney yesterday. No one, but no one, other than you, is going to protect you from financial ruin and mayhem. Do not trust your WH, not for one second. You can be nice to him and so on but do not trust him to protect you financially or any other way. Maybe he will but you can't afford to risk trusting that he will, if that makes sense.
The other bit of "advice" (which you are, of course, free to decide isn't for you) is to look at the divorce as a business transaction, nothing more. And that's why you need an attorney, a person who can view all the details without emotion because emotion and feelings have no place in divorce negotiations.
I would also encourage you not to speak to WH about anything, do it all via text and email so you have a record of what he's said (and keep in mind that he'll have a record of what you say so keep it all matter-of-fact and low key).
But to answer your questions, he's probably assuming that the marital home will be sold in the divorce and the proceeds split 50/50 and is planning to use his share to buy a new place. And that's why you need an attorney because 50/50 isn't necessarily equitable in your situation. If you have children and have been out of the workforce, the court might require him to maintain the family home until the youngest child is 18. Not saying that will happen but saying it's a possibility so that's why you need an attorney - to make sure you get everything you're entitled to and that you need. Find an attorney who will fight tooth and nail to get you as much as possible.
Additionally, some states in the USA allow the betrayed spouse to sue for monetary damages after adultery has occurred. Not sure if it's permitted in CA but it's certainly worth looking into.
Again, do not trust him. We've seen it over and over again, WS pretends he doesn't want a divorce or separation and lulls the betrayed spouse into thinking he's going to be a nice guy and that they can do the divorce on their own without involving lawyers and next thing she knows, he's taken all the money and left her with nothing. You already know he can be sneaky and cheat behind your back so if you believe he isn't above running off with all the money and leaving you with nothing, you're wrong.
Please get an attorney. Take the money out of joint funds. In fact, I took our joint savings and put it all in my name only until the divorce was final. Sent WH a copy of the new account number and told him I had the money and was keeping it safe from the 3rd person he'd introduced into our marriage and that every dime would still be there on the day the divorce was final and the funds dispersed. Not sure if I could've gotten in trouble for that or not but I decided it was easier to ask forgiveness than to ask permission so I just did it.
Hang in there and know that the things everyone here says is based on their experiences. Things happened differently for many of us but the bottom line is, you don't know which direction your WH is going to go with all this so take it all in so you can be prepared. You know we're all vested in having your back and making sure you don't get taken.