amdorsch,I know this is hard because you've gotten into a pattern. It's not as easy as just stop, bite your tongue. But why don't you try to change little by little? This is my suggestion for how to do that:

Start becoming aware of just how often you are lying. Maybe you could make a tally chart and mark on it every time you tell a lie. Don't go on to the next step yet. Do this for about a week and really keep up with it.

Then, start noticing when it is that you lie. Are you more likely to lie to certain people? In certain places? This will give you a good idea of when to watch for it. Do this for about a week, and continue to tally your lying.

Start replacing your lying with something else. Now that you've charted your lying for two weeks, you're starting to notice it as it happens. This is important because as you're more aware of your lying, you can stop it in its tracks. Maybe when you get the urge to lie, think of a compliment for the other person instead. Make it so that every time you feel that urge, you replace it with something positive. It could be a comment on the weather if you wanted, but I find thinking of compliments to be helpful (I don't compulsively lie, but I do have "need to tell" OCD which I'm trying to stop)

Keep practicing.

This takes practice. This is not easy. Get some support on this. Tell your friends you are working on your lying. Start correcting your lies -- after you tell a lie, and realize you did, try not to let embarrassment stop you -- tell them, "Oh, that was a lie -- I'm sorry!"

They will be glad you're admitting this. They will be glad you're trying.

A therapist might be able to help you, but only if you really want to change. It sounds like you are motivated to change, which says a lot! Many people who compulsively lie would NEVER admit they had a problem!