Interesting that she's thinking of separation, not quite divorce. A major difference between the two is that with a legal separation you're still married and possibly you would still be liable for her
debts surprise overspending splurges. Perhaps a consultation or interview with a local experienced lawyer or solicitor could forewarn about that concern and other traps she may spring on you.
Another lawyer question is what constitutes abuse in your local area. Is breaking items in the home considered DV? It could be considered a type of threat or control intimidation. A lot of conflict in a home may not be considered "actionable" but ask so you know where the line is drawn.
A separation would include a custody and parenting schedule, same as for a divorce. One possible risk is that if you later divorced, then you'd likely have to go through all the hassle of a second court process to make a new custody/parenting order and perhaps get a worse order.
Be aware that she may claim to be a Stay at Home Mother (SAHM). She's probably thinking that you will go away and keep paying all her bills because she is the mother. It would probably be wise when in any legal discussions with lawyers or court officials that you always state she needs to find her own employment or career. The last thing you should hint is that she's somehow disabled because of her mental health issues. (And never ever let it be claimed you or the marriage made her this way, unless you want to give lifetime support to a "handicapped" person.)
How and what to say when speaking with a soon-to-be-ex (stbEx)...
This is different than trying to repair the marriage where you both would share information to rebuild the trust. Rather, if the marriage is failing or has failed, then you limit what you share. Ask your lawyer whenever in doubt, or ask here, but one obvious topic okay to share is about parenting matters. Almost everything else... think twice or thrice before sharing in order to lessen the risk of being sabotaged.
One excellent handbook is
Splitting: Protecting Yourself While Divorcing Someone with Borderline or Narcissistic Personality Disorder by William Eddy.
