In the nicest possible way, I think you need to accept that MH issues often require professional support.
We all want to be there for our friends and family - but it can be overwhelming for people. And they may just not have the time or emotional space to help in the way that is required - over the long term, or in a particular moment.
She's your friend, not a therapist. Ultimately, it will damage your relationship to confuse the two, or to be resentful that she can't give you something she isn't, actually, equipped to give.
I also wonder if part of your feelings may be to do with projection? Did you set up a situation whereby you could be angry with your friend because you can tell yourself she chose her children over you?
Whatsapp is really not adequate to have a meaningful conversation. It is an enormously frustrating medium. There's a reason therapists don't do sessions over WhatsApp.
If you were genuinely distressed, I suspect your friend will have found the experience quite worrying - and perhaps even sensed underlying intentions.
I'm sure she cares about you. Why wouldn't she? I'm sure you deserve care.
But care for yourself, now, by refusing to turn this into something that could damage a potentially good relationship before you've had a chance to talk it over with your therapist.
You might find you feel quite differently after you've had that session.