You can’t. Peertube has to be on his own domain or subdomain (as I said for example here: Same hostname for two different instance? )
You can’t easily have Apache and Nginx running on the same public IP. For https to work correctly, both have to listen on the 443 port.
There are workarounds. The simplier is to use 2 different public IP for Apache and Nginx.
Here I gave some leads to another workaround, but it is not simple: Listen tcp4 0.0.0.0:443: bind: address already in use - #6 par JohnLivingston