What are you NOT including in this question? Based on what you actually say, they have no way to know you are dating, and no reason to CARE about your ages. DATING is perfectly legal. Sexual conduct would be in some states and not others. I didn't look up IL law. Unless you making out in the car, that would not be an issue for a traffic stop.
I remember your last question about abuse. This guy sounds manipulative. BE REALLY CAREFUL DONT trust him! If he is abusive now, I can assure you it will only get worse. I don't mean to be mean, but don't let him take your money.
It may depend on the laws of your state.
As a fiancee, I don't believe you have ANY legal rights whatsoever. If you signed on the loan, SIGNED, you are responsible for the loan, but it doesn't make the house yours, because you have no legal rights as a fiancee I'm pretty sure in most states.
You have to be ON THE DEED or married to have any rights to the house. I don't know if you signed any papers on the house or loan. If you did, you have legal access to that paperwork. Get it either from the mortgage company, or the Court House/deeds. Call the courthouse and ask them where to go to get copies.
If you are getting married, he should put you in his will or on the deed. However he can chnge the will anytime he feels like it, and you may not know. A will would give some relief for both of you that you will be taken care of if he passes, and the children will also. Without your name on the deed or being married (in most states) you have no legal rights to the house and I would be suspect of his love for you if he does not feel he needs to assure provision for you after he is gone.
Maybe you should put more assertion into expecting to be provided for after his death. If you don't seem capable of handling finances, he may only entrust this to his mother, however then you are also subject to her feelings and control. As his wife, he should not only assure provision for you, but also expect you to have responsibility with that money. Complicated. Talk to an attorney to see what you can do that would work out for you and the kids so you can stand on some firm ground when you discuss this with your fiancee. Many attorneys have a first consultation for free.