I think there's two separate issues here - one is being kept in the loop re work stuff and the other is feeling let down about your boss's behaviour regarding DD's naming day.

To be honest, work didn't keep me in the loop either about what was going on and I took it with a pinch of salt. I wouldn't have expected an invite to the Xmas party or any social event. Would have been a nice touch but not too fussed to be honest.

But I think it's all getting a bit blurred because your boss was/is a friend and it certainly sounds like she has 'issues' with your pregnancy/being a mum from the not giving you appropriate work to the not turning up for the naming day. Is it possible that she would like a baby herself and is having problems TTC? I'm not saying that excuses her behaviour but she certainly sounds like she's having problems coming to terms with you having a baby.

I think I would stop treating her as a friend and get back to a professional relationship. If you're worried about what the work situation will be if/when you return, call and ask for it to be clarified eg. were you working full-time and want to go back part-time?

In the meantime, I'd continue looking for other work.

Having said all that, I found that when I returned to work I was far less bothered about politics - I just go in, do my job and don't get embroiled too much. So as much as these things seem annoying now, you might find the same if you return to the same organisation.

Doesn't hurt to look at other options though!