It is always important to establish firm boundries from those who are willing to take and take. However, this might be an unpopular opinion in this thread but they aren't asking you for your advice. That is like a friend asking you for an apple and you give them a banana, only to feel upset when they don't eat the banana. It isn't about you. You are a component in what is happening. You matter as well, absoutely but no one is entitled to take your advice. Especially when it is advice that is not asked for. Sometimes they want your insight, sometimes they don't even want anything but to be heard. If you are not a listener, fine, you might want to take a second look at your conclusions for mbti but wanting to solve the problem makes sense. The problem however can't be solved by you. That isn't how life works. These people need to go on the journey and make their own conclusions to press forward. It is understandable that you feel "used and abused" but you are extending yourself in a way that isn't asked for it. A problem shared is a problem halved is your philosophy and applies to you- not them. Again, this probably sounds like I'm an asshole but you might want to take a step away from your perspective and view theirs. They are your friends.

As for myself, I pick and choose the ones I love carefully. They are few and inbetween. They can have my hear, my advice, my thoughts and feelings because I know they won't abuse them. It is vice versa. I had a handful of people who abused this but this was in my younger years. I simply phased them out when they feel entitled to what I can offer. That isn't enough justification for a doorslam. You teach others who you are.