I can't imagine how frustrating and disheartening this must be for you.
Here are some tips to help prevent further damage to the lace fronts
- When you trim them, be careful to keep the cut parallel to the hairline and even - any jagged edges are more likely to catch and snag. Personally, I glue the lace fronts down if they don't lie flat on my forehead and they are much less apparent. I've never had to trim one. Also be sure to a pair of very sharp scissors or Pinking shears to prevent further fraying on the lace.
Most monofilament wigs have some sort of welded lace in them. Do not pull directly on these features, as the fibers of these grids can actually separate, leading to tears and fraying of these delicate features.
REMEMBER: The lace on lace front wigs tends to be finer than the monofilament anywhere else on the cap. Lace fronts are therefore the most delicate parts of the wig!
Be sure you're putting on and adjusting the wig using the ear tabs and not pulling on the lace front to do so.
Now, to deal with the current damage. Trim that lace where it is frayed as much as you can. This will prevent having the broken grid of the lace stick up in weird ways in that spot. Only trim it where it's needed so you don't accidentally make the problem worse.
Also, treat it like it's pantyhose with a snag in it! Get some good clear nail polish and use this on the underside of the lace to help prevent further fraying. You may do this all around the lace front, if you like, or just that spot. When it it almost dry, gently use your finger to pat down flat any remaining parts of the lace that want to stand upright off the face. It may take a second coat, but the nail polish should sort of help seal that back down.
You can also use lace front tape to cover the torn area. Just press down firmly with your fingers to ensure the tape has attached to the lace, then carefully trim off the excess. Cover the tape using a sheet of regular tape of the identical size (cut it if you need to) to reinforce the region and keep it from sticking to your scalp, but this step is optional.
There is also a product I have heard of you can use called Fray Check and it is good for securing thread ends and combating fray issues. You can purchase this at your local craft store or on Amazon: https://www.amazon.com/Dritz-1674-Liquid-Sealant-0-75-Ounce/dp/B000YQKIDY.
I hope this information has been helpful for you and helps resolve your lace front issues!