I agree with the above.
Talk to the police. To the domestic violence unit. Get their take on it and advice.
If you initiate this meeting it doesnt mean anything formal. But they will make a note of it.
I really don't like the sound of male church elders visiting, to pronounce that everything is OK.
You need to think of yourself before your SIL. Yes you have 25 years of friendship but that doesn't mean you should endure more beatings, or become impoverished because you don't feel safe. She likes you as a friend. She will eventually understand. But stop trying to please her.
You don't need your DSs permission to just speak to the police. You can talk to them about it later but maybe if you did hear what the police have to say you might see that your DS need to start to understand what has happened to you and that your plausible church going DH is not what he pretends to be. Forgive me but it sounds like your son's have seen a patriarchal-led local community, where the men being in charge and the women subservient appears to be the norm. I'm not saying they believe that - just that they see it and so it looks relatively normal.
Your son saying your DH seemed to be cheery and normal after the event really sounds like your DH is lying his head off and minimising everything. So its not surprising that DS is telling you not to report it. But the truth has to come out and the truth may hurt but its better in the long run for your son to see that DH has consequences for his cruelty.
Also sounds like financial abuse too if you are paying 75 per cent of the bills and his lifestyle and having to protect your son's college fees. And your sons must realise that you wouldn't be wanting locks on your bedroom door if you were not really scared. Why does he contribute so little. What edoes he spend his money on. Imagine what it would be like now if you had been able to save that 25% yourself over the years.
I echo other peoples views that you need legal advice about the house. Get legal advice. Your sons will eventually understand and may even be more supportive if you do report this (report doesn't mean you have to press charges)
You shouldn't have to leave the marital home you have paid 75% for. Please find out what your legal options are before you act.
Ask your lawyer what the financial consequences to you will be if you leave the marital home (is it still mortgaged? in joint names?) and he defaults on the payments and taxes and utilities bills. He should leave. And you can sell the house and get your own place. Even if you have to hand him 50%
Maybe take the sabbatical after your've sold the house. Protect your job its really important
You are correct he is a criminal . Divorce asap so he can't get his hands on your future inheritance.
Sorry OP it sounds really tough but its good that you are staying safe.