If you want financial reassurance, develop an expense sheet and decide what expenses are essential or discretionary.
As for feeling awkward about your wife's inherited money, you two have been a team for years and you have made your financial contribution, so I suggest you just consider everything as combined assets.
When it comes to fear of letting your work colleagues down, believe me, they will get over it. None of us are as important as we might like to think. I handed in my resignation recently and I am quite sure my organization will do just fine. In fact, if you are in a leadership position and have done a good job, your company will thrive when you leave!