It's about you and you alone. Yes, it's too bad your buddy has dropped out, but for you to give up, too, is simply your defeat.
Your weight loss program has to be something that's independent of what other people do or don't do, what they say or don't say, what they eat or don't eat.
If you're looking for real-world support, you could join Weight Watchers or TOPS or some other local program. But whether you do or not, it's up to you to keep going. No one else.
Good luck! Don't give up!
You hang in there!