My LVN Mother Does Not Give Me Support

Hi. After having my 2nd child 3 years ago, I decided to change careers. After working in an office for over 6 years, I decided to go into nursing. I'm currently taking my last pre-req at a community college, and planning to attend an LVN program in May. My ultimate goal is to become an RN through an LVN-to-RN program. My husband and friends are all supportive, but the one person who I thought would be is not - my own mother who was an LVN for over 20 years! This is very hurtful, and at times she says negative things about nursing and I get the feeling she doesn't believe I can do it. Instead of encouraging words, she says things like, "Nursing is a very demanding job. It's not going to be easy." I am well aware that it's a very demanding job. I did a lot of research on the nursing field before I decided this was what I want. I'm not sure if she is this way because she hurt her back and knee over 15 yrs. ago while on the job, and now she's on disability? I'm afraid to tell her anything back, because when I have, we always end up arguing and her crying. I am so excited about becoming a nurse, but I cannot share that excitement with her, because all she is going to do is shoot me down by saying negative things. I do admit that whenever she says something negative, it encourages me even more to try my best! Has anyone else ever gone through this before with a family member???