How do people deal/recover from the betrayal

Of all the harmful traits and things a pwBPD can throw a persons way, the whole idealisation/devaluation cycle is the core of what I find so painful and difficult to recover from.

The idea that at the start you are made to feel like some ideallic saviour who makes everything feel so right. All their traumas + problems of the past are starting to be healed and they finally have a place where they feel safe. They convince you, that you are the one and they’ve never felt like this before and you treat them better than all their exes. They make you feel special and like the perfect piece to their puzzle.

However over time this starts to fade. Now they start criticising you and finding flaws and weaknesses in your character. ‘Why are you trying to fix me?’ And ‘I get scared of how you might react.’ Things you previously did that they loved become a flaw. They feel engulfed by the expectations that you never placed. Suddenly you start to doubt yourself and second guess everything. Eventually this feeling reaches a crescendo, where you feel the need to defend yourself against the onslaught of criticism. BOOM!

Now the pwBPD sees you as an aggressor and the person causing them this pain and suffering. Nothing you can do in this stage can calm them down and it’s like dealing with a separate personality. You’re either attacked and criticised or completely blocked out emotionally, both hurting equally as much.

As you attempt to pick up the pieces of your shattered self, you find that they don’t fit back in the same. As if someone cut up the puzzle pieces. You start to blame yourself for shattering their ideal dream, being the same as their exes or just for causing them pain. You begin to internalise all the negative words from the split and feel ashamed for not being their dream saviour. You might feel like a fraud/liar and this belief stems from the fact that you think you may have pretended to be someone you’re not and during their split they saw the real you. Even worse now they might have replaced you and this fuels the shame.

So for those of you who have come out the other side of this stronger and healed, how did you do it?