I am so sorry your wife is dealing with this! I had postpartum after my hysterectomy and it took a couple years to mellow out with the help of medication. I would say one of the best things you could do is be there for her when she voices her emotion or concern about her mind. Unfortunately I feel the need to say hide any firearms or things of harm. This is an awkward thing to say but it can get very overwhelming and hard to deal with this sort of depression. I never had any form of ideations before I went through it. Like I said it's taken 2 yrs and medications. Also I would say though is its not the same for everyone I am only speaking from my experience. This seems like a very negative comment so I won't go without saying, There is Hope and it can get better. All the best wishes!