it's pretty bad and not safe at all in a big city. So train in the early morning hours with a good group and be home before the rush hour starts, get in your car and drive to work.
Too many nuts on the road to be honest and going home is usually a lot worse than the morning on the way in, It's late getting dark and folks just want to get home. Forget riding on the same roads with folks sending text messages and driving with a phone stuck to one ear.
get out early, do some solid good training and head home, during summer do a race or two in the evenings after work or even start riding and doing training on a velodrome.
but, I guess I am lucky as I drive to work and get the kids after school 3 days a week so it means I just can't be tempted to commute. As much as I love the idea of cycling to work everyday and enjoying my self, where I live and work it just does not happen. I did live in other countries and cities in the past that have been much better for cycling to work and all erands, actually I spent a few years of car ownership making about 2-3k miles per year on the car and most of it was touring.
I've been racing and riding bikes since high school and I think it's in to my 23rd year, Wife and I met about 11 years ago, she got into it and since having kids she doesn't ride much anymore with a bunch or during the week, she will run most mornings and ride with me here and there. I can't convince her it's safe as she knows what it's like. I respect her not wanting her kids to have no mother and she does not bug me about training I do.
I hope the OP lives somewhere nice and is able to cycle without to much to worry about, also be glad your wife really is worried about you.