Friend – I feel a need to preface this by stating I am truly trying to help you.
I absolutely HATE it when posters come here and rant/whine/complain about the terrible situation they are forced to be in. Usually with some reason or excuse about how this is their destiny and there is no other option. Very often it’s "the kids", but you can also see finances, family... all sorts of reasons.
Look – if you decide to remain where you are feeling miserable, with no attempt to change it, well... go ahead and be miserable. Don’t expect changes, and any amount of whining won’t make anything better. But if you want change – if you want improvement – it will only come once YOU take action and make changes.
You insist you need to remain in your marriage, and – IMHO – use your daughter as your excuse.
I challenge that...
I think you will end up like all the others that say they are only there for the kids, until the last kid leaves, and then they find another "good" excuse...
I am 100% certain you can find all sorts of studies indicating it’s best for kids as far as family is concerned to be raised in a conventional father/mother environment, preferably in a neighborhood with like-minded, comparable income and even same race and religion, where the parents show mutual respect and caring to each other and to the children. Second best is probably some combination of the above, with some leeway on diversity where the parents show mutual respect and caring to each other and to the children. Third best is possibly a single-parent/shared custody arrangement where the parents show mutual respect to each other and to the children. Somewhere way below that you will probably find divorced parents who do NOT show mutual respect to each other, and at the bottom possibly a father/mother environment with abuse and no respect.
I am also fairly certain that a mixed-race, same-sex couple of different faiths living in a commune with people of all sorts, creeds, nations and sexuality can create the ideal family-environment for their children, as long as the parents show each other and the children respect and caring.
The common thread through the "best" situations is respect and caring. Much more than diversity or social status.
While checking the above out, you can also search for the impact of family-of-origin on relationship choices. We have a tendency to seek what we know, and to expect what we have seen. Women from abusive families tend to find abusive husbands, alcoholic families tend to find alcoholics...
Your kids... they are modeling their future relationships and expectations on what they see at home...
Chances are its too late for your older kids, but the youngest one – the one you are "protecting" and using as your reason to remain in misery... She’s learning that dad’s aren’t supposed to be happy, marriages are supposed to be confrontational and misery, and that there is no need for her to feel positive towards her future partner...
Think she hasn’t noticed you no longer wear the ring? That you don’t sleep together? Don’t think she’s heard the arguments and quarrels? Don’t think the kids talk together? No rumors? Really think they don’t know what’s going on?
IMHO the best you can do for your kids is to show that when you are kicked down to the ground and trodden on, you recover, stand up and move on.
Not saying you need to divorce. But you have to demand change.
Both from you, from HER and the marriage.
You state in another post that your WW plans to rugsweep and go back to the marriage. You also state her IC encouraged her to lie. You also talk about how negative this is all making you. How you have told her you plan to divorce once the youngest reaches some maturity (unclear on what that is – college? 18? Joins the Army?).
I’m going to encourage you to take a stance...
You have numerous options. Maybe not great or good options, but options to move your from misery to less misery, to less misery and eventually to content and even happiness.
I can make some suggestions:
Like... tell your wife that you are going to divorce once the youngest reaches a certain age, and whatever relationship you two have until then is purely functional. Don’t expect her to have any wifely functions, nor you as husband. This is purely functional to create an environment for your daughter. One of you moves into the guest-bedroom and you reach an agreement about how and whom you can date (if needed). Spend the time until D moves out to clean up finances and to facilitate whenever D is finalized. Then accept that she does whatever she does. Be that date the coach or go out all weekends or whatever. After all – this is only a relationship of convenience.
Like... Tell her that it’s best you two divorce and find the best way to do that while still being the best coparents possible. Use professional help (IC) to guide you, your wife and your kids through this process.
Like... Tell her how all that has happened has completely emotionally emasculated you and left you an angry wreck. How you don’t want to be that way and/or feel that way. That for NOW and probably the next six months you are purely focusing on YOU and your personal recovery. There is no focus whatsoever from you on the marriage. She can do whatever she wants, but what she does will show you DIRECTLY what your options might be when you feel personally stronger. Like... she CAN have her affairs and fool around if that’s what she wants, but in doing so she’s letting you know she doesn’t want you. She could help your recovery with assurance about her fidelity, but it would only be to help you decide your next step six months from now.
These are just ideas. Just something that IMHO sounds a lot better than remaining unhappy by reasons of yourself, alone.
Friend – I realize change is tough, and that nothing I suggest is easy. But there really is nothing easy about infidelity.