Lumari, I'm not a psychologist. I am one of those who found themselves in a situation somewhat similar to that of your husband. Or one of those who turned out to be - on the forums we really often write about ourselves in the feminine gender.
I understand your concern and sincerely would like everything to go well with your husband and son. But what "safely" means depends on who he is after all - a transvestite or a transsexual. From your story, one can at least understand that he loves both his son and you (in any case, he is afraid for you). So, all is not lost with the family. Further, you have probably already read how a transvestite differs from a transsexual. Yes, transvestites "play" women, but do not seek to change sex. In general, it is. But it happens that transvestites also have an idea to change sex. It was with me too, against the background of depression caused by the inability to realize myself. It is clear that transvestites will not pass through the medical commission. Transsexuals are also divided into regional and nuclear. And if nuclear ones almost without options get to surgeons, then marginal ones can still remain in the body that nature gave them. From what you have written about your husband, I can assume that he is either a marginal transsexual or a dual role transvestite who is in a depressed state. In general, it is difficult to judge from a distance in the retelling. On the forums, he is advised by regional and nuclear transsexuals who have gone through serious psychological tests ... and they measure your husband by themselves and wish him well. But good is, let's say, only for him, not for you.
Now about prospects. If I am mistaken, and your husband still cannot do without surgery (for nuclear ones, either changing the sex or in a noose is not a joke or a figure of speech), then a divorce, alas, is inevitable. True, as long as he has a minor child, the commission will not give him permission for the operation. There are options by the commission, but this is money. In a word, if he goes this way, you will have to decide: to be a stranger, girlfriend or life partner to him (even if it sounds strange, but this happens, although no registry office will register such a family). At least you are close people with him, you have a common child. Only you and your husband can decide, let the advisers arrange their fates. If he can do without surgery, then you need to understand: he will still not be a "man" in the classical sense. Most likely, he will be able to play a man in public, but he will need an outlet at least at home. That is, you will either have to leave him alone periodically, or take his feminine side. It will be hard to accept. Very difficult. Incredibly difficult. But if you can do this, you will be the closest person on the planet to him. His gratitude is hard to describe in words. But for you personally, this will mean that you will see a woman in front of you. You didn't marry a woman, did you? Have you imagined a long and happy life with a man? Will you be able to endure a new life? Will he be able to give up part of his female life for you? Or will it be easier for you to part with your husband? Do you need this cross? These are questions that only you and no one else can answer.
Questions about your son stand apart. A child can understand and accept dad in such a role. But he himself in the children's team may have problems if he tells that his father is a woman. Children are cruel. Difficulties will arise, if not in the garden, then certainly at school. This means that the husband will have to hide his feminine side from his son ... well, at least until he is 15-16 years old. Or maybe longer, depending on the nature of the child.
If you hope to "cure" him, then this is most likely futile. Transsexualism is caused by a congenital abnormality in the structure of the thalamus. This is not amenable to treatment. Transvestism is related, oddly enough, to alcoholism. The treatment is just as difficult. And since it does not represent direct harm to the body, unlike alcoholism, doctors simply try to reconcile a person with the disease. Wives of transvestites can find a lot of useful advice for wives of alcoholics.
In the short term, I will advise you to stop crying and remember all the good things that connect you with your husband. In a skirt and lipstick, he is, oddly enough, the same person. And his feelings for you do not depend on whether he is wearing socks or stockings. Try to accept it. Distinguish: when he will be a woman, and when he needs to be a man for you. Agree on how much money he can spend on his female image. Agree that he is allowed and what is not in relation to you, while he is in the women's. If you can, try to be not only a wife for him, but also an older girlfriend, help create a worthy image. But do not forget in any case that you are also a woman, that you also deserve to look beautiful and at least from time to time to see a man next to you. And then - talk to him, listen and talk again. Listen to your feelings. If you realize that you can live together - it will be great. If you decide to break up, it should be a mutual decision, without mutual resentment. But for now, know that transvestism or transsexualism of a husband is not always a divorce, it happens in different ways.
P.S. As a sign that you will try to accept him, buy him pantyhose. Or nice underwear. And then ... then something will happen. Smile, huh?