>>33385320 (OP)Sounds like social anxiety. Practice is probably the only thing that will help, unless you want to try paying for therapy or whatever.
Start slow with lower effort things to slowly get out of your comfort zone, and ramp up. Start with being around people even where you're not especially expected to speak (e.g. go to a cafe and read a book for an hour?). You can later ramp it up to joining some hobby, activity or volunteering group where the focus is the activity itself and not specifically socializing?
Don't forget non-verbal stuff and body language. Even if you're not talking, a casual polite smile or nod when you see a person comes/passes nearby.
>I just think things that I should say, and then don't say themThink about why you do this? Trace back your thought process and make a plan to change something next time it happens.
And the hardest part is probably taking care of yourself. If you have a drinking problem, the rest of your life is likely not great either. There's no quick and easy solution, get off your ass and put some work into it. You will fail, but don't stay in the fail state for long and try again.