I know what you mean. The idea that if things are so bad for so long that something inside you always tries to hold you back from progressing. Not something conscious but almost like something inside you is afraid of getting better because it is totally new territory and then you wont be sure who you even are after that. Sometimes abuse can get engrained into our identity (although abuse doesn't have to define us) and without it we are afraid of feeling lost- even though we work to get rid of our abuse issues. So i see why you may feel that something is holding you back from progressing in that way.
Also sometimes we feel so bad about ourselves that we don't fully feel that we deserve to get better and then the self-destruction kind of mechanism comes in. Or maybe you feel that this "is too good to be true" and so you don't trust the progression that you are making.
But it is always like this isn't it. When one thing improves something else usually gets worse, for a while. But things come to us and appear to us at different times for a reason. And this is just something else that your inner self wants you to work on. Often you have to open things up and things get worse before they get better. It is like a building site- it often has to get messy before it gets made better. After all, lots of this stuff goes right down to the roots.
You will get through it. I have sleep problems still, and one method of overcoming it doesn't usually work for long, so i find it best to use one method of making me sleep better for a while, and then when that stops working i switch to another. I guess it is like in war, one battle tactic only ever works for a while before the enemy catches on. By using many different battle tactics we will win the war.