Why do you lie to me?

A coworker blabbed to the lady (J) I job share my blind student with. J wanted to back off of the student's team next year because he's going into grade 7 and it's a hard year and she wanted to give him the transition year before high school. This coworker went to J and told her that she might want to stay with the student because I was pregnant. HOW THE FUCK IS IT HER BUSINESS?!

Then J spoke to our boss lady when she sat J down to talk about the student for next year. Boss already knew and J asked discreetly to test the waters and see if boss knew. That's okay, that's fine. So boss comes to me today and tells me I might want to be careful who I tell. I was confused and then she told me that that lady had blabbed to J. I was almost in tears.

So I confronted the coworker as non confrontational as I could. Asking her "did you tell J?" and she said no. So I told her what boss had told me and asked if maybe she overheard her talking to someone. So she says that maybe J overheard her and I talking.

After school I talk to J and apologized because I should have been the one to tell her, not the other lady. I asked J a couple questions and J tells me that no, she didn't overhear, she TOLD her. I double checked that it wasn't a "GUESS WHAT?" type of thing and it wasn't but when I heard the real story, it wasn't much better honestly.

It WASN'T her business. My mom is a boss too. If she was that concerned about our student she could ask my mom what was going on. But NO, she had to go and stress J out and pull this shit on her.

Poor J is stressed to the max. When her stress levels go down a bit, I'll confront coworker who told. I just don't want coworker to stress J out more at this moment. So as far as work is concerned (mostly that coworker actually), I'm not talking about the baby. I'm not sure what I'll say, but thankfully there's one week left (plus half day friday for me) and then it's spring break for two weeks. After that, I'll be out to the admin (principal plus the boss that I had problems with last year) and soon after I'll be out to the whole staff.

This coworker was my friend. I need to confront her to save our friendship, if that's even possible at this time. I'm not sure I can trust her again after she LIED to me.

Edit as of Apr 20: I confronted her last week and all is good now. She told the truth and we talked and now I don't even think about it anymore when I see her.