Is my mother reverting back to childish state of mind?

a little info... My father ped away almost 11 months ago. All 3 of us children still live at home with her ages 24,21,19 (if that matters) but, within the last few months I have noticed that my mothers personality has changed for worse. She will act really strange... she won't talk to anyone when she is mad... and when we ask she has a weird look on her face and she says really quietly and harshly "I'm fine" she has been listening to conversations between me and my sisters fiance... (she never did that before) and just acting weird.... especially since I've been dating this new guy... he is absolutely amazing (i just got out of a really bad long term relationship where he ended up raping me) but, for once I am truely happy with this man. he is the love of my life... and is my prince... he has never done anything bad to me...but, whenever I even mention his name my mother gets upset and angry... and she won't say why... you would think that she would be happy for me right? instead she will walk around slamming doors and cabinets... another thing is... I just got a new job that happened to be at the place my mother wanted to work after my father ped away.... When I came home with the good news... she hugged me and told me that I'm too boney and I need to gain weight...She didn't say congrats or anything... anyway, I can go on and on about her... but I won't...I don't know what is going on with her... but I've just about had it... I'm about to get up and leave... Has anyone else ever gone through anything like this? is my mother losing her mind? Sorry it was so long... but I appreciate and advice