Son’s girlfriend diagnosed with BPD

I agree with grandmabatty

Unbelievable that she didn't let you know you our son was in hospital. Her BPD is likely to cause all sorts of problems. Speak to your son - God luck.

It sounds like your son's girlfriend is sending you these very unpleasant texts . If she is sending them - then he has to do something about it .
You haven't said which type of BPD .
Sadly , I notice this Cuckoo mentality is quite frequent .
I hope that the situation resolves happily for all of you .

Yes, you need to speak to him. From what you have said I don’t think he sent the text. I’m rather shocked that his girlfriend didn’t tell you that he was in hospital - that’s a red flag.

We had some very strange texts from my son's phone - turned out they were actually from his wife (now ex-wife thank goodness)

Then don't assume. Phone him and discuss it. Just listen to what he says and tell him that it's given you food for thought and you'll consider his views. If it was him.

I assumed he wrote it..but it’s so out of character.

Yes, Grandabatty, that was first thought too.

Did your son really send the text or did his girlfriend get hold of his phone?

Hmm. Are you sure that he wrote it?