Where to find a Caregiver support groups in Baltimore or Howard County Maryland?

I moved in with my 87 year old mother a few weeks ago and it is not going well. We have always had issues getting along since I was young. When she feels bad and knows she needs someone then I am the greatest for moving in with her. She defiantly has dementia. She goes through spells where she hears and see things. She will be very nasty and say hateful things to me, but later says she doesn't remember it happened. I can't do anything right. She has always seemed to favor my brother. My father died young and I think she replaced him in her mind with my brother. He has admitted over the years and especially recently she can b e mean and hurtful. He pushed for me to move in with her and I felt guilty so I finally agreed. He said I was a Saint for doing this. Now that I am in he doesn't want to hear about the problems. How can someone be so hateful to the person who has changed their life around to move in to help her? She has always thought people were "out to get her". She once thought the neighbors threw dandelion seeds all over her yard because they were jealous of her flowers/yard. If you don't agree with something she says she can't agree to disagree, instead she gets an attitude and will say something mean and nasty. I knew I would have challenges with her but I am getting ready to have surgery for a kidney mass, not sure if it is cancerous yet. All I do is cry because I don't know how she can be so mean. Please let me know of any support groups in my area. I feel like I am going to have a nervous breakdown if this continues.