Hmmmm, I don't know a lot about E Bikes, myself. All I can offer is advice on the wheels and physical part of cycling, in that you need to watch your wheels and spoke tension when you are a heavy rider. Take it easy on rough roads, and get out there and enjoy the riding.

Now for the physical aspect: Take it sensibly. You may find that you want to go strictly human powered. It will be a process, though, so take joy in your increases of capability. The pedaling will help with your weight loss and CV health as well as your blood sugar management.

Now, the tires, 65PSI tires aren't safe at 80 PSI, in my opinion. 70 PSI should be, though. You also need to be sure the rim can handle the overpressure as well. Too much pressure can spread the rim walls and this will ruin the rim. You might look at some 100 PSI slicks, though, presuming the rims will handle the pressure.