Hello Dazed

17 yrs is a long time to be with someone and even though you have been struggling with the relationship and your own mental health issues over the last 5 yrs, it is understandably really tough for you right now. I can hear there has been a huge amount of conflict and upset between you and your wife. How are you, and is it your son, doing after all that has gone on?
Despite all the upset I think I can hear that you still perhaps want to talk things through with your wife. Do you know what you want from talking to her, are there things you still need to sort out?
The situation on Facebook sounds upsetting and is clearly meant as a message to you that is also causing you pain. Is there a way that you could be in contact that causes you less upset than looking at her posts? Maybe take some time away from Facebook so you can think more clearly about what you want going forward.
Looking after your mental health and prioritising your needs are your top priorities at the moment. Do you have a support network in place for yourself, family, friends a therapist? Being with someone who has BPD often means our needs aren’t prioritised and we neglect ourselves, try and use this separation (I know it’s hard as you feel hurt and possibly confused) to reestablish some self-care and post here about how you are feeling and want your immediate plans look like.
Let us know more about how you are doing.