I think my mother is undergoing depression

I'm a 19 years old college student, It's been a year that I moved to another city and I only get to see my family during hollidays...My mother and I used to be very close but she has been acting weird recently: she stays alone in her room all day long on the internet and finds herself exuses to be upset or angry for no reason, she's always mad at my father and says that she wants to leave him, I know that my father isn't perfect, he's not affectionate and we barely see him due to his work, when he is home he prefers spending time with TV than with us, that gives my mother every right to complain about but to leave him after 20 years of marriage?...That's not the only problem, she is starting to rejecting me, saying that I'm selfish and that she doesn't have to care for me anymore cause I'm old enough, today I got so upset about her treating me badly that I've decided to confront her with it but she only got more angry and said that I was finally showing my true self: An ungrateful evil child , though I did nothing to her...Another thing: my mother used to be a very neat person, cleaning the house everyday, cooking healthy food etc...but recently when I arrived I was surprised with the state of the house,we often get junk food for lunch she stays in her room with the computer all day long, relying on me or my sister to do houseworck, it doesn't bother me to give help but I can't do everything wich gives her another reason to blame me, when I tell her that I have to study she says that it's not an exuse and that she doesn't care about it. But the biggest problem is that I don't have this intimate relationship with my mother anymore we were more thant best friends and told each other everything, now whenever I try to talk to her she's either too buisy to listen to me or doesn't care about what I have to tell her. Do you think that these are signs of depression? Do we need the help of a specialist and how to get my mother accepting help? I want my sweet mom back, I want her to enjoying herlife instead of staying home on the internet, she should go hang out with friends, find herself a hobby, cause now she seems to be disconnected from the rest of the world, her behaviour is unbearable and the only one that she seems to still appreciate in the family is my little sister...

Mental illness is a tough one. Some times it's caused by things going on in the body like diabetes. Sometimes other things. I would hope she could go for testing, but honestly, when you're depressed, you don't really care. You let yourself go, and the house, and you blame everyone for everything. If you can talk to her, tell her you love her deeply and are worried and to please see a doctor and have some tests done. She will feel better about herself after a while, and the house, and life in general.