The usual risk attached to cheating is that you get discovered. Now in your case, if it's a one-off, a long time ago and so forth, that's probably not going to happen now. Another risk is that you are less motivated to pay attention to your partner if there is someone new taking up your thoughts. Again, that doesn't seem to be the case.
The real crux of the matter - and where the cheating is relevant - is that it is leading you to ask if it happened because the relationship is bad. I'm not going to speculate why you cheated but, on the strength of what you've more recently written, I don't actually think the relationship is particularly bad. And I'm usually the first one to look for signs of bullying or control.
He says he wants me to have a social life and feel better about myself but if I go out for an evening with my friends and don't get home till midnight he then says I'm a bad mother for staying out so late.
This could be an example of setting you up to fail.... but equally, were you clear that you'd be out until midnight?
I say I want to loose weight he says go to the gym then
On the face of it, that's a sensible suggestion for someone wanting to slim down.
He doesn't have to be a bad partner to be the wrong partner.