Hi OP. Very sorry you are having to deal with this mess.
Some quick questions first.
1) Has her affair been exposed to her family (sorry if I missed this) as, IMO, they will need to take the leading role in her mental health recovery?
2) What is to stop her trying this all over again when you divorce her?
3) Assuming you are the father of your child, what are you going to do about custody because, given her past actions, I would have real fears here? At best, she will neglect the baby, at worse, she will harm or take the child’s life. I would never be able to leave my child in the care of a woman who did all this.
4) Why hasn’t she been sectioned under Mental Health Acts?
5) It seems pretty obvious she will never be able to work in her chosen field again (might get a job stacking shelves). If you divorce, how is she going to support herself and what effect will that have on how much you have to pay?
My wife and I have experience of suicide in our family and it’s impact. This is going to be harsh but, in cases like this, the person committing suicide is a coward. She wasn’t trying to free you to live a good life after her death. She was trying to leave you in a permanent state of guilt and despair over her death that would be a life long sentence for you and your child. She wanted you to be the one who found her, for those images to be burned on your brain forever. Her selfishness carried right through to what she thought would be her death. No thought for those who had to find her, no thought for those left behind except extreme selfishness.
From your description, I am pretty convinced this was a real attempt to end her life, not one of these "fake suicides". I don’t think it will be the last attempt either, especially if you divorce her.
So, she has you caught between a rock and hard place. Do you leave and run the risk of her suicide or do you stay to look after her and your child? You have to applaud her cunning but then it takes a lot of cunning to have a 5 year affair?
Personally, I would have her committed to a mental health facility so that she is looked after properly which would also allow me to live my life.
For those who would condemn me for this post, I speak from experience here and know the damage that is done, even after 35 + years. Walk a mile in our shoes!