If your hair follicles are strong enough, your hair should be able to survive a very gentle finger detangling in the shower. This probably means that you should really work both on your retention from the inside, so your can then take better care of your hair from the outside. We recommend checking if you have any deficiency like vitamin B12 which would create weak follicles as a consequence. An immediate alternative you can try is to find a conditioner that adds a lot of slip to your hair and let it sit for a good 10min before rinsing. Even without any finger detangling, using a good conditioner will already help to reduce the tangling and allow you to have a decent style while you are fixing your follicles from the inside. Don't despair, you are asking the right questions and will find your way out of your hair loss!