Oh gosh, I'm sorry to hear that. I used one for years and now I use a Dexcom, but I still use a Libre on my diabetic dog.
Make sure you clean the area with something like alcohol or some people apply it right after a shower, but you want the skin clean and completely dry before you apply.
First I always push hard on the applicator when attaching/extracting? the sensor in the second piece of of the applicator that actually has the sensor in it. Then when I apply I do press pretty hard and hold it there for a few seconds. I kind of do a circular roll press around the edges to make sure it's attached well. When I go to remove it I gently rock it back and forth working it slowly off. Once when I couldn't get the applicator to detach from the sensor on my arm I had called Abbot and they said to push it back down harder, that did work for that one.
In my case I am using Skin Tac to make sure it stays on my dog and I wait for it to be tacky so it is actually even harder to remove without pulling the sensor back off. So I try to use my finger or a set of tweezers to feel the edge of the sensor, there is a little bit of adhesive around the outside edge that you can hold down to gently work off the sensor.
I believe if you call Abbot they can walk you through the application process, they do want it to work for you. Several people on this site use a Libre so hopefully more come along to help and you can figure out what is going wrong to your process of applying it. There is always the possible bad applicator/sensor though too.
I hope this helps!