I'm sorry to hear about your nail problem.
Strangely enough, certain things about your nails can signal certain things, such as ridges either horizonally or vertically. It can mean that you have a deficiency of some type...or even a fungal infection.
I have two recommendations and both will sound strange. I'm not going to get into my experience with fingernails, but let's just say....I have lots of it.
Vicks Vapo-Rub massaged into your nail and cuticle will actually help with fungal infection and help oil the nail up so it's not so brittle. Do it for a few days and keep a band aid over it while you're doing things that you do that tend to cause a snag.
The other thing is to wash really well with an antibacterial soap and dry your nail throroughly.
Cut a tea bag more or less in the shape of your nail...but allow a little room along the cuticle and edges. Put a coat of clear polish on your nail and immediately apply the tea bag. Gently pat down to make sure that it sticks and there are no air bubbles. After it's dry, apply a couple more coats of clear polish, allowing to dry in between. If there are any rough edges at the tip of your nail, you can gently file it off after everything has set.
The tea bag becomes pretty invisible and if it feels a little rough, you can file the surface of the nail to try to smoothe it. But unless you intend to wear colored polish, it's not really necessary.
This can be done with super glue also, but I wouldn't recommend it unless it's just for a temporary fix for a broken nail if you're going to a wedding or special event or something.
The nice thing about the clear polish and tea bag is that they can easily be taken off with nail polish remover to let your nails breathe once in a while.
I don't want to offend anyone, but I never had a single problem until I made the mistake of getting some acrylics at a nail salon. I know many women who do it all the time, but it completely ruined my otherwise healthy nails.
They're back to normal now...thank goodness. But it took a long time.
Try the tea bags and hopefully each time you change them, you'll start to see new growth and eventually be able to just trim the bad parts off little by little.