The guilt of 'being present' while still working is killing me

I leave the office at 5:30 most days, home by 6. So I'm there for dinner, bath time, bedtime stories. Sounds perfect right? Except I'm checking Slack the entire time. Last night my 5yo asked me a direct question three times before I heard him because I was reading an email about tomorrow's standup.

I put the phone down for 30 mins of quality time and then I'm back on it til 10pm finishing work. So what's the point of being "home" if my brain isn't actually here? How do other people actually disconnect?