You surely must make up your mind. Do you like her as a friend or do you want to be her b/f ? I don't think you know that answer yet, your post shows that very well. Think and decide, then if you need anything else return to here
By the way, what's wrong if you ex get mader at you. She's your ex-g/f, you probably don't want her back do ya ? So why do you care if she's mad at you or not ? A small detail it's that your ex may try to poison your relationship.