Ecstatically shattered ego

1. Does "ecstatically shattered ego" here mean "extremely"?

2. Does "threat of stability and integrity of the self that human sexuality is" mean "human sexuality is a threat of stability and integrity of the self"?

3. Does "which" refer to "sado-masochistic practices"?

Context:
The formalisation of destruction in the art encounter allows us to repeat the painful pleasures of what theorist Leo Bersani calls an ‘ecstatically shattered ego’, which is a repetition of the originary ‘threat of stability and integrity of the self that human sexuality is’. Needless to say, this is very different to conservative trends in art that view it as a civilising form of transcendence over the human condition as well as to sado-masochistic practices, which, by contrast, organise the unbound energy of the ‘ecstatically shattered ego’ into a series of contractual relations, rather than allowing for the mobility and indeterminate sensuality of desire (Art and Psychoanalysis by Maria Walsh).