So, lets break this down by villain, shall we?
Turns out, she left Ireland because she was scared of the British Men of Letters.
Thats also why she sent a letter, because she found a bug in her place.

Credit: Jack Rowand/The CW
But was that real?
Thats the question Marys asking herself as she also remembers flashes of being tortured.
While Toni takes Mary for another session, Dr. Hess holds a meeting with Crowley.
Also, they used to sleep together back in their school days.
And speaking of people Ketch has slept with, Mary asks to see him.
But its not what you were hoping for: She turns it on herself.
Ketch is there to stop her, but she continues to beg for him to end her life.
Aside from her family, all shes ever had was her will, and now shes losing that.
She doesnt want to put the people she loves in danger.
But all Ketch does is promise her it will be over soon.
Okay, now were back to the fake meeting that Sam and Dean set up.
(That last one doesnotsit well with Dean.)
But by the time they get Toni back to the bunker, the BMOL are waiting for them.
Sam and Dean come out victorious in a shootout… until Mary shows up.
The boys along with Toni, whom Ketch leaves behind will have two, maybe three days to live.
Dean tries to break through to Mary, but it doesnt work.
Shes too far gone.
Whatever rig was keeping Lucifer captive starts to reverse itself.
Suddenly, Lucifer can control Crowley.
Lucy makes Crowley hop around on one foot.Yeah, this cant be good.
Hes back and fully powered, and his first matter of business is killing Crowley.
Or so he thinks.
Just before Lucifer stabs Crowley with an angel blade, Crowley notices a rat next to him.
If Crowley had died, there wouldve been a reaction to the blade.
But I guess Lucy is too caught up in his freedom to care?
Aside from that Lucifer not noticing anything weird tidbit, I really enjoyed this episode.