Running (in and of itself is not bad) on the knees nor is their any journaled evidence, that lots of running causes arthritis and the like etc.
As member mentioned, cycling is very good cardio activity without the kind of impact outdoor running can have. Swimming is even better and much easier on the body. No matter what activity you pick, the important thing is to take your time and ease into an exercise routine, not to mention getting a checkup before starting.
Don't dismiss walking. It too is of great benefit. The problem is a lot of people don't get their heart rate up (at all or much at all) during their walking for a variety of reasons, and it takes a little longer to get the weight off.
Try walking briskly for 10 mins and then walk for 1 min. Do that several times to talk with and over the course of several weeks, work your way up to longer periods of brisk walking or slow jogging.
And in my opinion, it is wrong for your dad to berate you about your weight etc. Realize, that when he is doing that, it really isn't about you. It is really about something inside him, and he is using you as the verbal punching bag. Try not to take what he says personal. Take it one step at a time and do the best you can each day. No shame in that.