Hi Lily, so so sorry to have to meet you here on this crummy board. For someone just one month past BD, you are doing remarkably well.
I agree with Ellie (KML) that you need to protect your son and yourself immediately. That is the most important thing right now. Get yourself your own debit card, and then use money from your joint account to consult with a lawyer about child support, and to find out your rights as an unmarried partner of over 16 years.
I read your post on Angela's thread, and you sound like a pretty natural born DBer! When I was in your position, I was still in that crying/begging stage You are doing great. I know that your heart is broken and that you are spinning and angry and hurt, but please remember what you told Angela - this is NOT about you. The OW is not about you. She is a skanky old dirty bandaid that your temporarily insane SO is using to try to make himself feel better about himself. But, it won't work for long, will it, as she sounds equally crazy. Cadet will tell you, these MLCers "affair down" - way down, scraping the bottom of the barrel.
Hang in there Lily, and keep posting. I think the more you post, the faster you will get off moderation.
Linda
Me 65, Ex 64 M 38 y 2 adult S, 4 G-Kids MLC 11/07 BD 12/09 D 3/14 Dating nice guy 7/14 Engaged to nice guy 12/17