Sometimes the kids we raise aren't 100% programmed the way we would like. They are their own people, with strengths and flaws and even some BS attitudes. That isn't necessarily a reflection on your parenting. Your kids have been influenced by so many people and experiences.
One of the things we have to deal with is the transition from "kids" to "adult children". They may or may not need us to be friends with their friends, for example. And we don't know everything they went through in relationships. Your daughter's ex, for example, has been sober for 4 years - so what was he like in their relationship? Maybe he wasn't such an upstanding person, maybe she doesn't want his sobriety history to be public in terms of its connection to her, etc.
What you have to do is give her space, as others have said. Let her cool down, let her miss you, let the children ask about when they're going to see Grandma and Grandpa. You say you "want to be a pest." Really, that is the worst thing you can do. It's what YOU need, but it's not what SHE needs, and therefore it's not what your relationship needs. If you do not think your relationship with your daughter can survive a separation of 3 or 6 or 12 weeks, then it's not very strong, is it?
This is dredging up old wounds, of her being angry and you getting her message that you weren't good enough. So it's not just about FB, is it?
My husband has 2 daughters. For some years now, only one has been in his life at any given time. They have issues, they retreat, they hole up in their lives. Both are in abusive relationships (one physical, one mental/financial) and their lives get crappy and overwhelming. So we wait it out. Eventually they come back.
You want your daughter to know that you are there for her. She knows it. She cannot manage it right now. You have to be the uber-adult now, the patient person who shows confidence in what you have one as a parent, and not the anxious person in need of validation. She cannot manage the Needy Mom. She cannot, apparently, manage the Friends-with-my-boyfriends Mom. If she uses FB for work, she absolutely doesn't need any references to her personal life on there.
But you say there have been issues for years - now they are just at the forefront because they're on social media.
Also, you bring your own experience with your own parents into this, and maybe you are trying just a little too hard with too little confidence in the outcome. You have no choice - back off, wait, calm down, breathe, wait some more. If you keep nagging her, she will never settle down.