Thanks for your question. Your letter is full of hurt and mistrust, and if I am reading you right, he has also abused you physically, as well as emotionally. You are concerned for your children because they will miss their daddy. He says that he loves you.
OK, lets look for evidence of these things - what positive things does this man bring to your children's lives? How much negative stuff do they see and how much would they benefit from being away from that negativity? Children are very perceptive and can sense that parents are unhappy even if they do not see the anger or the abuse. Often, when a parent says 'we are leaving' the children say 'thank goodness, why has it taken you so long?'
Of course you feel weak - you have asked your husband to respect your wishes not to watch porn or to use the one-way door and he has not respected you. He makes you feel weak by not hearing what you say. He is looking into wife-swapping - not only does this mean he is willing to go with another female, but that he expects you to have sexual relations with another man. Ask yourself if this is what you got married for? Is it what you had in your dreams when you said that you loved him and would do so forever? I imagine that he has broken his original vows by his behaviour, which in my view, gives you permission to leave.
He is begging you to stay and saying that he loves you - I would say that he does this because with you by his side, he is a respectable married man - without you he is a single lonely man who seeks sexual gratification where he can. I am supposed to be non-judgemental in my replies, but I have to say that I honestly believe that his behaviour towards you does not indicate that he loves or respects you. His behaviour is abusive and unacceptable. Our children learn from the role models that they have and I feel certain that you do not wish your children to become like their daddy. Of course they love him because they are small. But this love will disappear as they become older and more aware of what he is doing to you and then you will have stayed for nothing.
I cannot make this decision for you - it has to be your own. I hope I have spelled out what you already know in black and white for you to read. There are people who can help you to leave - do you have family or friends who can help you if you decide to do so? there are also websites that you can use for support - try www.womansdivorce.com/leaving-an-?abusive-husband.html or
There are many women who stay in sad marriages, but there are many who leave and find happiness with or without a new partner, whether or not they have a family. If you leave, please ensure that you tell the children over and over that it is not their fault and that they could not have done anything to prevent it, as children often blame themselves. Let them know that mummy and daddy both love them very much and that it is not their responsibility to make you happy. They need to know that you are in control. I do hope this has helped you to see more clearly.
Please consider pressing the accept button if my answer and my time have been valuable to you - this is the only way we get paid on this site. Or feel free to reply. With best wishes, Sarah