How do I stop being scared to go to the dentist after not going for more than 15 years?

I am 25 years old and the last time I've been to the dentist was when I was 7 or 8 because I had a cavity. My family is uninsured and we were never able to afford health care, let alone dental care. My parents are hard working people but they couldnt afford the dental care. I work part-time and go to school. I found this federally funded health clinics with dental clinics which has a sliding scale for those are who insured. I have an appointment coming up, but I am so scared and embarred as to what the dentist might think. My teeth needs a lot of work, crooked, odor, etc. How do I stop being embarred?