I think some people find it easy to use people who are open to helping them. It is important to learn boundary lines, and realise that sometimes helping someone else is hurting yourself. There are a lot of people who would expect you to go the extra distance without blinking twice, but would never do the same for you if it were the other way around. I think you must be a really caring person, and people like to prey on that. Cutting those people out of your life is great though. Now you have the ability to use that time and energy on meeting and socialising with other people that value and respect you.