Mind reading is a cognitive distortion. Do a google search on cognitive distortions. They are not healthy and can lead to lots of problems.

Steve is 100% correct. The last thing you want to do is try to get into her head - it is a cheeseless tunnel. It is completely futile but will have you going around in circles for hours. Detaching is the opposite of that. It is getting present in your own head and letting her go. I know it is rough but you need to let go and accept that your MR is over, that she does not want to be with you. Once you accept that you can start making progress on yourself. The one refrain that I have read over and over here is that it is only once you completely let go that there is any chance of her coming back.

Hang in there.

W 34 Me 42
Married 7 years together 8
0 kids 1 beloved dog
BD 4/6/2018
I moved out 4/7/2018
I moved back in alone 8/05/2018
I file 3/06/2019
D official 5/7/2019