Letsgo, Ive read your post a few times because the first time I read it I thought to myself this lady doesnt sound very happy, and its something I still feel after reading it twice more.
It all sounds very sad and all because you mistakenly think that separation is easier in the short term.
You sound as if you've settled, settled for a marriage where you hardly ever say to each other 'I love you', and where you've found a convenient excuse for (no romance, passion, feeling that someone's really into you)
To be frank your marriage comes across as being half dead, and you sound resigned to also feeling half dead. One day there will be no young children to blame on (no romance, passion, feeling that someone's really into you) and for sure that is when you will wonder where you're life went and why you settled for (no romance, passion, feeling that someone's really into you)
And please don't think you're children wont grow up knowing something went on, or mum and dad aren't that close because they will, they'll notice your marriage and you are doing them a great disservice by presenting it to them as to what marriage is, as well as what being happy is.
I can recall my children saying to me - it was good you eventually decided to separate mama because we can now make new memories of you as the woman you once were. We wont have to sit years from now feeling sad because although you tried to make a go of it you were obviously not making it, and life was passing you by. In fact its just yesterday my middle child, my 31 year old son said to me - Im so proud of you ma, you just don't know how proud I am.
And I would just like to add that separation or divorce doesn't mean you have to move on to someone else, I certainly don't intend to. It's more than possible to be on your own and be happy.
Life really is too short for settling and for feeling resigned to no romance, passion, feeling that someone's really into you) . You deserve more than this, your children deserve more, and to be honest - so does your husband even though what he did was horrible.
I separated after being married for 36 years and like you I also made excuses for a lot rather than face what was actually going on.