You aren't ready to be in any relationship. You don't trust him and you never will.
Obsessively wrecking your brain, checking his possessions, spying on him, and deleting his accounts isn't healthy.
You are treating him as if he is a child.
You cannot have a healthy nor productive relationship with anyone like this.
Whether he's cheating or not, this relationship should end. This relationship is unhealthy and dysfunctional.
If you've been tolerating him cheating you on, stop staying. If he promised he would change, he isn't unless he wants to.. He isn't going to stop. No amount of what you are doing will ever make you trust him or view him in a positive light again.
You cannot control his actions and behaviors, you can only control yours.
Respectfully, You do not need to be in another relationship unless you perhaps find the root and solutions in therapy.
Work on your self esteem and worth too.
Respectfully, work on providing and being a good role model and example for your daughter.
Stop exposing her to dysfunction, and work on your dysfunction.
You don't want her to wind up someone's doormat, and being paranoid with worry and fear that she could be cheated on. .so much so that she's making herself sick, and unhappy...do you???
You have to teach her to be strong, recognize red flags within herself, situations, and others...you have to teach her not to settle for dysfunction.