Just speaking from my own experience...
My two have long hair. And I'm not the best at keeping them combed daily. When their hair mats up, I use a leave-in spray conditioner and work through the knots with a brush. I hold the hair as far into the root as possible to gently comb the hair without hurting them. It can take a long time, sometimes an hour each, to comb through their hair. After bathing, I again, use the leave-in spray conditioner to comb their hair out.
When I walk them outside during the winter, I tie up their hair, so their hair doesn't drag on the ground. After each and every walk, I always wash their feet off, regardless the weather or the month of the year. The salt is really damaging on their paws. Not only that, if they lick their paws, they can get sick. So it's super importantly you wash their feet if there is salt on the roads or sidewalks.
But don't feel too bad. You are definitely not the worst dog mom in the world! The hair will grow back.
Most groomers will always suggest to shave offs mats. They don't have time to comb out mats of all the dogs that come in. lol