That's a positive step forward you are taking, going to see your GP. I would echo what everyone else is saying, please just be honest with them and tell them everything which is going on with you. You need help.
Don't worry about getting upset in front of the doctor and falling apart.....without sounding too cold here the more desperate you appear in front of him/her the more likely you are to get a referral for counselling first time round, if that is what you would be interested in. Hopefully you will get a full health check as well.
Remember there is also AA, where you can walk in a get instant help and support when you are ready.
Take care.