Changing behaviors that had been typical in the past is one way to change oneself. Instead of reacting to a person/situation, take a moment to reflect and change your typical response. If in the past you've allowed others to make decisions for you, find ways to make these and carry them out. You've mentioned being passive. Since you've got this insight, use it to your advantage. Habits can be broken but your approach would have to change as well as your expectations and internal dialog.
This would happen with practice. If you catch yourself undermining yourself, then you'd want to correct that thought and act the opposite of what you would have done in a similar situation in the past.
There may be some fear/hesitation on your part to assert yourself because once again even subconsciously you mean fear disapproval or rejection. As a result, you self sabotage yourself and the other person "wins" again.
These individuals being close to you would know your vulnerability. Because of that, you would have to think of a reaction that would surprise them.
Different tools can be used to change behavior depending on what you feel comfortable with. None of these would be instantly effective. Autosuggestion is one tool that allows for the shift of inner dialog to your advantage. CBT is another.
The tools are out there. which one you chose and apply is up to you as long as you allow yourself to explore what works for you and not give up. Some take longer than others to bring in the desired results.
How to Manual:AUTOGENIC TRAINING - Karl Hans Welz
The Art of Saying NO! (Setting Boundaries)
Self hypnosisYour Power Within! Self Confidence through Hypnosis
Not sure if you're asking about what to do when you meet w/ the attorney or if your question was of a more existential nature (how to avoid toxic relationships)
1) You know which people are toxic to you
2) you know how they do it
3) you know you're passive and accommodating
as a result
A) practice changing your expectations of these individuals (they won't change for you) A tool would be- write down what they've done in the past, how you reacted to it, and then make a new list next to it of how you want things to be and how you'd act differently this time.
B) When you feel cornered, remember that saying "No" can be a complete sentence!
C) decide which therapeutic tools work best for you- hypnosis, autosuggestion, one on one therapy, bibliotherapy, etc.
D) Focus on what you feel, think, say and do and NOT so much what the other person is doing or saying. Mainly, think of what outcome you desire to achieve.
Some of these suggestions can be used right away ex: autosuggestion (manual included), self hypnosis through Mp3 downloads, making a list/journaling, monitoring your thoughts-inner dialog and reframing negative thoughts/ to positive ones when it concerns your behavior. Asking yourself what's in for me and writing a list to allow yourself to see self defeating patterns is another.
To face the passivity, a task could be to chose at least one of these and try to apply it to your advantage today.
"Friends" who are "less than supportive" are not friends. Perhaps the way you see them needs to change too. It may be disappointing to face the fact that they're using and abusing you and you'd have to severe the relationship as much as you can.