one year is up and its time to go down

Hi my name is Brittany and today is my first day on this site. I am 23 years old 5'2. I have not been in shape or at a healthy weight since i was 16. I have been with my boyfriend now for just over a year and in that time I have put on 20 pounds. I am now at a big 168 lbs bigger than i have ever been. :( We have just recently moved in together and it is really hard to avoid the same snacking habbits etc that he has. before my lifstyle was quite different ie: only drinking alcohol on the weekends when i was out dancing with my girlfriends. now i hardly go out dancing and like to have a cold beer in the hot tub on week days while relaxing with my man. I need help!!!! any one else in my same position. how can I stop these bad habit?