While this is extremely difficult for you both, I would suggest your husband sticks with his gut feeling. If he wouldn't marry them if he didn't know them, as has been said, why would he marry them just because he does?
He should stick to his principles. Not because of the difficult relationships surrounding the wedding etc, but because it his moral belief that he should not marry these two people.
One should stick to ones morals, no matter how hard it is to do so. My parents, both catholics, had a moral dilemma with my second eldest brother. He was to be married in a registry office. Not even a non catholic church just a registry office and he was doing that because his bride to be was (and still is) an atheist. She would not even consider the idea of a church blessing. Due to this both my parents separately and individually decided they could not attend the wedding. It hurt my brother hugely, but I strongly believe what my parents did was right. We all had the choice to go or not - I chose to go.
I think mum partly regrets it but at the end of the day her morals were strong and she stuck by her beliefs and I respect her for that more than anything else.
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