You seem to be suffering from bulimia nervosa.
Bulimia nervosa is an eating disorder and involves Binge eating and feeling of tremendous guilt for doing the same. It often involves purging as in your case. As panic sets in and you turn to drastic measures to "undo" the binge, such as taking ex-lax, inducing vomiting, or going for a run.
Important thing to remember is, purging does not reduce the calories and that is the reason why many people with bulimia put on weight.
It is a treatable condition and can be resolved. I would recommend the following-
1) The first step to recovery is to admit to you that you have a problem and work towards improving it.
2) Seek professional help who will be able to schedule regular therapy sessions and prescribe medications.
3) Avoid people and places that will trigger Bulimic response.