Ms. Cheryl, i am so sorry to hear that. One thought is if you have a long break where your son won't be in school for a week (spring break) tell him he's grounded, no friends, and take away all of his toys/games and tell him he needs to experience the full week as a gurl so he behaves better and learns his bad behavior has no place in your household or society. He will object and say horrible things but be strong and after a while without playing his games he will relent. (It's important to know that what you are doing is a gift, it's good, it's positive, it's right. It's not punishment it's helping him be a better person). If you need to be more extreme remove all of his clothes and only have girl clothes to wear he will relent after a while
When you show him his panties, skirt etc he will reject it. Ask him why. He'll say it's girls clothes and he's a boy. What's wrong with girls clothes. He'll go on about how girls are weak etc. Well you're a woman does he think you're weak and inferior. He will feel shy and say no because you are his mother. Tell him it's not his fault that he thinks this way but it's wrong and hurtful and you love him and want to help him. Now be a good boy and put these on. As he's getting dressed remove all of his boy clothes. Remind him it's only for a few days. When he's dressed compliment him. Make him feel great feminization should be positive, it shouldn't be humiliating or degrading. Have your daughter be positive towards her new sister as well. Tell him in order to earn back a priveledge he needs to write a one page paper on why women are strong and the unfair treatment they have received for a thousands of years. Have him research the percentage of women graduating med school, law school, to show him female leadership is the future
Have him read his paper to you and your daughter out loud. I bet you will see his behavior change quite a bit. Have him help you around the house. Call him mommy's little helper, your sweet boy which eventually will become your sweet little princess. Have him next to you as you put on makeup and ask if he would like to try some on and make him admire his pretty look in the mirror. The more caring and positive the experience the more he will crave it. You are a single mom with two kids which means you are amazing, strong, and Powerful. You are doing the right thing for your son, and even for your daughter who will see the result of loving female leadership. I wish you great success and happiness Ms. Cheryl. Thank you