It’s her own fault there.  She shouldn’t of snooped on my phone and read my private thoughts.

EXACTLY. And from what you’ve said on here, your feelings for your ex weren’t really a secret to your girlfriend to begin with, right? She knew you still loved her and yet chose to stay with you, knowing she was 2nd in your heart. That was her own choice. If it were me, I would’ve left the minute I found out I was second place, and if she had done that, that alone would’ve prevented her from feeling the way she does now.

She had to switch SCHOOL DISTRICTS to move in with you?  If you are feeling guilty because you feel like this was all somehow your responsibility, I would try to reframe things in your mind. This wasn’t just you. She is a mom, and she really should not have done that in the first place, especially so soon in your relationship. This definitely isn’t your fault, because she could have just as easily NOT moved in. That was her choice, too. And it’s not like you two were married or even engaged. It seems like you are taking a lot of the blame onto yourself, when this really seems pretty 50/50. It’s both of you.

I know this isn’t going to be a fun thing for you to do and that you feel bad about it, but, hopefully, this will all end up being a good thing that frees her up to find someone who is truly a match for her. And the same for you.

I would talk to your kids before you have them stay with their mom all that time to see what THEY would rather do. It might feel to them like you’re trying to push them away during this time, even though that’s not your intention and you’re just trying to make things easier on them. They might rather want to deal with it just so they can spend time with you, so I’d definitely check with them first to see how they feel. And, if anything, you should see if your girlfriend can just go live with her mom for a while.