How can I build up my self-esteem and confidence?

I've been struggling with my weight for the past couple of years. I've always been fit, but I put on about 60 pounds throughout university. I really struggled this past year and I've been doing a lot of nothing. My social life is pretty absent since I don't want my friends to see how much weight I've gained, and I've also not been working. I finally JUST started a new diet/workout plan and I'm taking the necessary steps to lose this weight and get my old self back. The problem is I'm still highly sensitive, and have a very low self-esteem level, as I just started my diet. I recently got an offer for an interview at a really good job within my profession. For some reason part of me hopes I don't get the job. I know this is because of my low self-esteem and fear of working again, facing new people. My weight has really put a damper on my social life as I said. How do I get past this? This is a really great job and it would help my career as I am a new graduate, but because of my personal issues part of me is telling myself I hope I don't get it.