Hello Molly, a warm welcome to the site and thank you so much for posting your comment because you have made many friends already, although some people just read and don't reply doesn't mean they don't understand what you're saying, they do and hope you feel comfortable, we have your back.
Being lonely in a marriage or partnership is not exciting what's so ever and this will affect how you feel about yourself and with your children, although we know you love them, but it's hard to do this when you aren't happy yourself.
Trying to put on a brave face can work for a short time but as time progresses this even makes it more difficult to smile when you aren't getting the support you think you should and will begin to change how you react to different situations.
Can I ask if your friend in Newcastle talks about herself after listening to you, and if she does she is also feeling the pain you are suffering from herself, or she may be too worried, and I say this because we always think that the person we're able to talk with don't have any problems themselves.
Are you able to tell us whether you are renting or buying because this may help us to continue any advice we can give you to perhaps separating from your husband?
My best wishes.