If you do not take your baby out of the state, there is no danger of being charged with kidnapping. Even if you go out of state, you should be fine. However, let him know that the baby is OK so he does not file a missing persons report.
You should make sure you have access to funds, so withdraw funds from any accounts you have access to. Take all important papers with you just in case you don't come back right away. You would be entitled to spousal and child support under these circumstances if you file for divorce.
Here are grounds for divorce in IL, including adultery:
You may want to look at this later when you are in a better emotional state. But you should consult with a local divorce attorney at some point. The state bar association can refer you to attorneys in your area.
Make sure you keep the proof you have of adultery in a safe place or more than one place so you have it if you decide to file for divorce.
Here is information also on prenuptial agreements in IL: http://www.gitlinlawfirm.com/qa/premar1.htm#setaside
Again, I am so sorry you are going through such a difficult time, especially while you are pregnant. Please try to stay calm for the safety of your child and unborn baby until you have people around you who can provide moral and emotional support.
All the best to you.
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