Okay, you are past one hurdle already... you've concluded there is no expectation for reconciliation in the future. With that addressed, the priorities now come down to you (1) as a reasonably normal individual and (2) as a father.
You are "currently under a police FVIO". My guess is that it is temporary and not a "final" order or decision. It is vital that you don't acquiesce or give up. It always looks bad and devastating at the start but the reality is that if it has reached a court there are several steps involved. Each time the other side tries to get you to admit guilt or to agree to "anger management" which in itself is a sort of admission of some culpability, it is up to you to defend yourself.
While you may not be 100% innocent, there are mitigating circumstances due to your spouse's history of conflict, rants and rages, not to mention suicide threats. Do you have any documentation or witnesses to her poor behavior?
While young children cannot be directly interviewed ("in camera" appearances in court) they can have their own legal representation assigned, known as Guardian ad Litem (GAL). The GAL would represent the children's interests, not you or your partner. You may have to ask for a GAL, just be aware that not just any GAL may be helpful, find one respected as unbiased and experienced by the court and other associated experts. The GAL can recommend to the court what they observe and recommend to the court that the children receive their own counseling.
I don't know which precise process or court you're in but likely a good step for you to take is one all family court cases start their parents with... parenting classes. If you get a good start at that, it gets you on the right track. And of course getting some level of legal guidance so you don't make the common clueless mistakes many here did when they first encountered the legal arm of the law.
We know you're concerned for your children, that they may have extended time with their problematic mother. All of us parents whose adult relationships failed have faced that, you're not alone. One good thing is that courts have a general mandate to try to enable parental relationships with their children. So a good perspective is that while the court may defend the "victim", they also should (hopefully) consider the circumstances leading up to the incident. This is where your legal defense can properly clarify that this was a reaction to repeated long term goading and without a previous pattern. That separation is a good outcome to avoid future conflict.
Your ex may allege you've been abusive to the children too. That's common too. The court may order you, as the alleged perpetrator, to take a "Psych Eval" or other assessment processes.
If at all possible request that any investigative orders include both parents. If you have any documentation of her BPD diagnosis and history, ensure that is presented and considered too.
This is important. Since there was NO abuse of the children on your part, the court should eventually conclude the children are safe with you. If this process has not already started, you should NOT let matters sit overlong with their mother in unchallenged total possession. You have rights as a father which are up to you to defend.
In my case, my spouse was facing Threat of DV charge but gained temporary custody and temporary majority parenting from my family court which defaulted to preference for mothers. At the end of the divorce, after cursory Psych Evals and an in-depth Custody Evaluation, I walked out with shared parenting and equal parenting time. A few more years and I gained full legal guardianship. A couple more years and I obtained majority parenting time. Yes, it looked hopeless at first, but gradually court made positive steps for my parenting.
Remember that it is up to you to decide to remain in your children's lives. You can fight for your rights to be a parent. There are uncounted split families out there. Generally, the children spend time with both parents, using a schedule in a court order. (see the quote below) It is wisdom to seek as much parental time and authority from the start. But even a lousy order can be improved upon in future years, as many here have done.
Living in a calm and stable home, even if only for part of their lives, will give the children a better example of normalcy for their own future relationships. Staying together would mean that's the only example of home life they would have known — discord, conflict, invalidation, alienation attempts, overall craziness, etc. Some 40 years ago the book Solomon's Children - Exploding the Myths of Divorce had an interesting observation (the earliest quote I could find) on page 195 by one participant, As the saying goes, "I'd rather come from a broken home than live in one." Ponder that. Taking action will enable your lives, or at least a part of your lives going forward, to be spent be in a calm, stable environment — your home, wherever that is — away from the blaming, emotional distortions, pressuring demands and manipulations, unpredictable ever-looming rages and outright chaos. And some of the flying monkeys too.