Then I would leave it in. In no way, shape, or form, would I leave your kids without a way to get hold of you in your current situation. The only other option is to get that 4th line from TMobile and use it as the “house phone” if you can trust that your husband won’t take off with it.
Another option is if it makes financial sense, is to swap it out for a WalMart $15/month “landline,” but that is WiFi dependent. When we got rid of cable and landline, dropping the “bundle package” only saved us $30 a month. But I was so annoyed at our cable company that we did it anyway. But my kids are older, and I am usually always home, and my kids all have cell phones on the “one flat rate for the entire family” from tmobile.