Need an experts advice

Ok so I have a relative (female in her late 40s) that I believe has a mental health problem... But I'm not exactly sure what. My hypothesis would be depression/obsessive thinking, but I still think tere is more, here's why, please tell me what you think.
Right so ill start by listing what I believe to be odd behaviour:
- obsessions with tarot cards and what isn't around
- preferring to be alone rarer than in the company of others (but out of choice)
- always has something negative to say about all
Of her 'friends' there's always something 'nasty' about theim
- slight lack of hygiene, just small things such as not brushing teeth or washing face before bed
- doesn't believe that her husband loves her, although he is tryin to clearly and showingly make her happy every single day, and she still believes he is a 'bad' person
- from witnessing arguments she believes she's been so wronged in her life, so badly treated, she has an actually DNA incapability of saying sorry. She just doesn't believe she is wrong ever, and if accused of something she goes mental and will start screaming (literally screaming) and crying saying everyone gangs up on her
- she totally acts like a spoil bratt ungrateful when people buy her presents or gifts, there's always something not quite right with the gift.
- she always makes excuses up for socialising
- with age her wothdrawal to socialising has got worse and worse, and when she meets new people she doesn't know how to act 'correctly' toward them.

The main problems that are present here I would say is lack of respect and approximation of others. She also has a complete different thought process to everyone else, and doesn't cope well with small drama.
For your information she is also very overweight, and doesn't know why. Because she denies responsibility for this she also doesn't even try to diet.
It's been bugging me for a long time, I think if I could find out what exactly might be wrong with her I could try to help her - find the right things to say before she just becomes to self absorbed and shuts off completely from the world.
All help and advice very much appreciated.