Mr. Kruger,
I will respond to each of the points you made...
Thank you for the prompt reply! You're welcome. It may take me up to 2-3 days to respond, but generally I will try and respond within 24 hours.
I would say hours to 2 weeks or so. A week before and during her period is often a trigger, but not always. There’s certainly a hormonal element involved too.Hours are consistent with BPD, 2 weeks is consistent with rapid cycling Bipolar, the two (or more) conditions can exist at the same time (comorbidity). I also noticed, when my uBPDw had her periods it would also trigger my wife as well - I have observed the hormonal element as well; however, this is not a symptom/trait of either BPD or BP1/2; but could be PMS or PMDD or something else. I am not a licensed professional, and I cannot diagnose. If at all possible, get her into a licensed professional for an assessment. If and when you do, do NOT mention that you think she is a borderline, instead, focus on explaining in detail, each of the symptoms that you see, most practitioners do not like you doing their job for them
After the episodes usually she will talk through some sort of resolution that makes sense to her but not to me. But, since she’s calm I go along with it.#MeToo, I will generally validate what I find to be valid (her feelings). However, I will not validate the invalid (her version of facts, which are often a 'false narrative'). Like you, I have learned to dance around her eggshells, and not trigger her as much as others do.
I’m currently hiding in the basement because an outdoor rug that she bought is “ruined.” It’s somehow my fault. Same here (usually something other than a rug though). Borderlines, more often than not will not accept responsibility for something that happen and will more often than not blame someone else for it happening - 'blame shifting'. Generally speaking they are too full of shame to admit that they may have not done anything wrong, and in the case of my wife, until recently she could never admit to doing anything wrong, and as such, she could not apologize for her behaviors, as she genuinely could not recognize that she was doing them. This is perhaps the most frustrating aspect for me, as I feel that she cannot recognize her negative contributions to the relationship.
The whole situation is difficult we have a special needs son with a severe disease and that exacerbates the stress. It’s not a fun environment but I’m trying to hang in there to keep the family together and so our son is taken care of best. I think you have hit the nail on the head, that it is a 'not a fun environment' - which I feel is a dramatic understatement. I am curious as to what condition your son has? The reason why I am asking, I also have a daughter who had severe anorexia nervosa; however, with intensive care she has been able to put it into full remission. I too am 'trying to hang in there' to keep the family together - some days are better than others.
When I landed here 15 months ago, I was at a loss as to what to do to make things better, I had only learned of BPD a few months before that (June of 2022) after my wife had attempted her most recent suicide attempt by taking heart medication.
I am going to offer up several tips, on how to manage, cope, learn about the disorder, and what to do about it - I suspect it will be just as difficult, if not more so than taking care of your special needs son, as you also likely have a special needs wife as well. I know it feels like I am cursed in this regard; however, my higher power is using me for the greater good, in ways that I would have never previously envisioned.
Now for my tips...

Self-help books, there are so many books out there, I have a short list of the - these two are the best ones for starting learn about BPD, learning about your 'caretaking roll', and how to manage your pwBPD (pw = person with) so you are not so stressed.
The best book for learning about BPD is
Stop Walking on Eggshells: Taking Your Life Back When Someone You Care About Has Borderline Personality Disorder by By Paul T. T. Mason, Randi Kreger - Make sure you have the 3rd edition, as it has an excellent assessment tool in it.
I am going to point you to another book that has a lot more teeth for managing a pwBPD, that book is
Stop Caretaking the Borderline Or Narcissist: How to End the Drama and Get on with Life by Margalis Fjelstad - this one is the best for managing a person with BPD. A summary of the book can be found at
https://margalistherapy.com/articles/borderline-and-narcissism-issues/handbook-for-dealing-with-a-bp-np/ where she specifically states that you need to tell yourself:
+ I did not cause it.
+ I cannot control it.
+ I cannot cure it.

- Please do self-care. You need to 'fill your cup' first, before you can help her with this. It is kind of like the announcements to put your own oxygen mask on first when flying before helping the person next to you with theirs. You need to have enough energy for both yourself and any you have left over can go for caring for her, and your son too.

Don't do this alone. I have an individual therapist, I also attend groups that I find supportive as well. I also believe in self-help resources that I also use many of which are free/low cost resources.
If you are looking for BPD specific help, you have this website, BPD family, you can post and ask questions 24/7 here - in my humble opinion this is by far the best resource. NEABPD has also been mentioned, they have a long wait list, but they have a lot of videos. I am a strong believer in self-help resources - like youtube, books, etc.
If you are looking for weekly Zoom meetings specific to BPD, sponsored (but not attended) by Randi Kreger, author of "Stop Walking on Eggshells" series of books at
https://groups.io/g/MovingForward - look towards the bottom of that page for the list of Zoom meetings, some are general, others are specific.
If you think you are co-dependent, according to Google 90% of us are, CoDA can be helpful too (CoDA.org), it is not BPD specific.
NAMI has a group is for parents and/or partners (about 3/4 parents) of children with mental health disorders including BPD and other severe mental health issues which share a lot of the same challenges caring for a person with BPD. The group I attend is 'in person' which I find is more authentic than a Zoom meeting or posting messages.

Set strong boundaries on not accepting bad behaviours, especially rages - the "Stop Caretaking" book has some excellent tools for this. Also,
https://bpdfamily.com/message_board/index.php?topic=329744.0 is a series of workshops to help you out as well.

Ask questions, get strategies from myself and others who have had similar experiences to your own, figure out what works, and use that.
Take care with self-care.
SD