In California, there is an expectation that divorcing couples split their marital property 50-50. For you, that's simply not going to work. Your spouse is leaving you for another person, and they've been spending money from your shared account on that other party. You want to make sure that you get your fair share out of what you own in your marriage, but you also feel that you should be repaid for all of the money you put in your account that went to pampering your spouse's new partner.
This kind of situation isn't unusual during a divorce, and it's something you'll want to talk to your attorney about. While California's laws do assert that community property is to be split, you could negotiate outside of court or make a strong case for a division that isn't 50-50 when you go before the judge. There may be exceptions made for cases like yours, especially if you can show that your spouse wasted the marital assets.
Another thing you'll want to do is to try to prove that as many assets as possible are your private, personal property. If you have receipts or information showing that you received items as gifts, you may be able to claim those assets as separate property and prevent your spouse from claiming them during the divorce.
This is a complex situation, so it's a good idea to talk to your attorney about the very minimum you'd be happy with taking with you after divorce. You've been through a lot, but they will be there to help you seek a fair settlement.