Hi exmuslimah
First of all, you are not alone feeling like you do when confronted by these facts. But what you shouldn't do is hurting yourself, cutting yourself or try suicide because your husband chooses his beliefs over you. It hurts, it hurts a lot. But remember that Islam teaches its followers from the start that martyrdom and loss of wealth, life and loved ones for the sake of allah is the highest pinnacle of faith. This is typically for all new cults and sects (look at the early history of Christianity), but once the religion has established itself it doesn't stress this as much. Islam, however, has never let the martyrdom doctrine go because else it would never survive in my mind. In your husband's mind, he is probably going through a major trial and he thinks that this is just a sign that allah really loves him. Now it is up to him to choose "right" in order to deserve allah's love. It's sick, but indoctrination has a very strong hold on you.
Don't tie your happiness and well-being to another person, your husband. You can still find happiness elsewhere. You have two small children who need their mother, especially now in this situation. Where do you live? If you cannot live with your husband anymore, then I advice you to seek legal help asap and make sure that you don't loose your children to your ex.
You are not the only convert who was basically tricked into the religion. The relationship that Islam offers between the all-mighty, all-forgiving and "merciful" (not so merciful when you start reading about it) is very simple but beautiful. But once you start reading about the history of Islam, its many rules especially concerning anyone that is not a free (non-slave) adult male and finally its misogyny, one can start seeing Islam for what it really is. False and man-made. Hell is such a brutish and UN-merciful place that not even the most sadist evil person could have imagined all the intrinsic torture methods for seemingly mundane and harmless actions (oh, I didn't believe in allah who doesn't need my worship anyway and now I will spend eternity in hell despite the fact that I didn't have an eternity to figure this shit out). Paradise is VERY androcentric with only men in mind. It's also very simplistic. Women have no place in paradise except being the spouse of their husband and giving birth to children
Please seek legal advice, and if you are feeling so depressed that you have contemplated suicide, get in touch with a therapist or a doctor so that you can talk about your feelings. It is not healthy for you to keep all this inside. I hope you can use this forum to vent all your thoughts and emotions just like I have done. You are not alone in this!
Topic: polygamy in "jannah" led me to leaving islam