@ OP, I reviewed your website. I personally feel this Christian might have been over dramatizing the situation. IMO, there weren't any demonic overtones but you did seem to express some dark (as in depressed and moody) thoughts and the language was a bit abrasive at times, even in some of your most-recent posts. Maybe this is the vibe she was picking up on; however, if she hadn't been so overzealous in her efforts you might have been more receptive to it and perceived it in the light it was intended. Don't let this damper your spirits. Not all Christians are like that. I'm sorry you got bashed by another Christian for simply being yourself while aiming to better yourself through Christ. That happens more often than you'd think. Find the silver lining in every rain cloud. Ask yourself, what can you take away from this experience? Are my actions on par with Christ's teaching, what my pastor says in church, etc? Check out my avatar.
Iow, don't simply write it all off as useless criticisms and personal attacks. A lot of us tend to do that. Oh, that person was being judgmental. They don't know me. Their behavioral critiques were nothing but insults and filled with malice intent. They are just jealous. And, this ^ happens way more often than the former. But there's a grain of truth in every tooth. So, consider how you are portraying yourself to the outside world now that you are saved. Use this moment as an opportunity to grow and mature in the things of GOD.
1 Corinthians 13:11
11 When I was a child, I talked like a child, I thought like a child, I reasoned like a child. When I became a man, I put childish ways behind me.
In the Body of Christ, there will never be a day when GOD and Christ will call on us to stop evolving. The person you are today will not be the person you become 20 years from now. Everybody's got to start somewhere, why not start today? Instead of using her behavior as justification to remain the same, reverse this decision and find ways to improve within yourself. You can't please everybody and I'm not suggesting you even try. I'm saying take a long hard look at that woman in the mirror and ask yourself, where might I have gone wrong to cause this reaction? Since NO one's perfect, no one's ever 100% blameless except Christ. So evolve and continue to go to church, but avoid this person in the future if she can't stop obsessing over you. God bless.