Friend or Foe?

If your friends want to do social things with you, how do you decide if they can be trusted as "healthy" friends?  After 49 years, I am still afraid of hurting feelings when I go out for dinner.  I met some friends out who I hadn't seen in a few years.  My plan was to be very good, no alcohol and smart dinner.  Well, I had one cocktail and a TON of food AND DESSERT.  It is possible that I just can not go out socially if I can't make wise choices????