Good Afternoon, alias First of all, what I write is merely my own opinion and not necessarily etched in stone. In fact, I often change my mind based on responses. Please don't be so quick to judge mom and this is why. I admit she doesn't sound involved with your son's schoolwork.
Teens are hard to raise.
There may be some leftover issues regarding your moveaway in the past or your lack of early involvement. Children tend to tell us what they think we want to hear so it becomes natural to judge the other side because we think we have ammunition which may not even be valid. As for a latch key kid, your son is 13 and being home until 6 pm is not that big of a deal at 13. This would be critical. This is not meant to be sarcastic,I am just asking.