OP, I clicked on this thead expecting an early realtionship, few months in, he isn't honest with me type thread, and my response was going to be that you cannot make someone understand that honesty if important if they don't think so themselves.
Having read your posts, my response remains the same, except that your husband has repeatedly and deliberately demonstrated that he does not give a single fig about being honest with you. This is not new information to you.
Either you accept that he constantly lies to you and that it drives you to distraction, and you swallow it all down forever, or you leave.
Either your kids learn that honesty is just a silly little thing that mummy wants but really isn't that important, because look! Daddy gets away with it all the time, silly mummy. Or you show them that there are consequences for dishonesty.
And the fact that he is taking out loans and lying about it or, even worse, gaslighting you while fucking family finances, is the nail in the coffin for me.