Newton, welcome to this forum. Many of us, including me, have been in your shoes, so we understand. It'll be hard to fade, because you're too visible as an Elder, but it's possible. Step down as soon as you can and let the dust settle for a month or two. Don't accept any "privileges" in the meantime. If you have a neighboring congregation, start attending meetings there now and then, and make sure your congregation elders know about it. Be vague about your reasons. Then, start skipping a meeting now and then. In time, you know you will start be perceived as 'spiritually weak', which can be hurtful, but it's the price to pay.
Your daughter will be grateful to you that you took this decision. My son certainly is to me. It made a huge difference in his life and personallity. If your wife leaves with you, what a great win! Let us know of your progress. And don't feel guilty, it's a waste of energy. Focus on what's to come and help your family.
Eden