He's sort of a Svengali... It means someone who's manipulative. More than that: somebody who makes you think that you need him in order to accomplish anything.
Everything has a price. The price, however, isn't always money.
If someone keeps bringing you down, perhaps it's time to get up and leave
Please do not become so hurt by life that when someone loving comes along, or something good happens, you resist allowing the love and joy in.