You shouldn't let someone invade your personal space. Checking through your phone, Social media, and all. You need your space.
Make you feel insecure about yourself (Ever) about anything. Don't let her disrespect you in any way and never let you do things your way.
Don't let someone Rob you of your hopes, dreams. Talk you into self-destructive things when you don't want too (drugs, partying).
We all share Gifts and that's okay but if someone is asking you to buy things you can't afford, just don't force yourself. Don't let her use you for money.
Alienate or take you away from your friends and family. You should not corner everybody b'coz you found someone. Remember when she will leave, they will be the only ones to handle you.