I'm confused, should i just file for divorce it's not fair to put my wife through all of this?

I love my wife always have and always will. Am i in love with her? yes..most of the time i know i am. But what does it say when i'm still thinking about the woman who i cheated on my wife with? Earlier this year, I told my wife that i had been cheating on her and we separated for 3 months.In June we started marriage counseling and i thought it was working, we talked out our problems and we made progress or so i though, it's been a good 7 months, my wife is 4 months pregnant but last night, i made a mistake. I met up with the woman i cheated on my wife with, nothing ual happened, we met at a public restaurant but before i left, i kissed her. Only she can do that to me, I thought i was over her and all that bullsh*t, but i'm obviously not. I don't want to put my wife through that. It might sound selfish but I think i'm going to file for divorce because I need to figure out what i want..without hurting my wife and the other woman, yea she's the other woman but i care about her a lot and she doesn't deserve it either. I need to figure out where my head is at. That's a valid reason for filing for divorce right? That doesn't mean I won't be there for my kids, we already have a 2 year old and she's my world. It's not that i'm unhappy in the marriage i'm just indecisive. I don't know what i want. I don't want to blindside my wife with the divorce either what am i supposed to say to her? After all that counseling, nothings changed. It was never anything she did. It was just me...