Lets set the story first:
I am living with this girl who I do not see (in any way shape or form) as being attractive. There are six people in this house so I haven't specifically gone out of my way to live with her.
She told me earlier this year that she had feelings for me. I was as blunt as possible, told her to just stop thinking about it because it will never happen. Anyway, she mentions it again about a week after that and this time I tell her to shut the f-up about it - and only found out she liked me after signing the year contract for our house.

Anyway, here is where I need advice.
I went out this week (about 6 months after the initial chat with 'obsessor') and found a HB9 (girlfriend material), worked the pickup and took her back to her place (SNL). My 'obsessor' knew I went back and then proceeded to ignore me since it happened. Yesterday, I invite the girl to mine which she obliges and we get on really well (awesome), but then my 'obsessor' throws a strop and has a huge go at me.

She tells me that I have to appreciate her feelings more. Firstly I didn't realise that she still felt that way, secondly I don't really think that this 'obsessor' has any right to get between me and being with this HB9.

I know the old rule that you put bros before hos applies (even if she is a girl bro), but I haven't known her that long and her hatred for me being with any female other than her is driving me away as a friend.

I need some advice!
tl;dr
I have an obsessor who I live with (contract signed before she told me) - I am a student, therefore stuck in this house so can't move.
I met a HB9 in a club who is interested in starting a relationship but the obsessor is hell bent on getting her way which is that nothing happens.

What do I do? Its such a sensitive issue.

EDIT: We had a run in a while back where she massively cock-blocked me on a night out. Also my housemates are bored of this - hence why I need advice to sort it.

I think you"re doing ok so far. You have got to tell that crazy chick "look, I do not have any sort of romantic feelings towards you. I am sorry, but it is best if you just get over me." It is unreasonable for her to think you can't date women because she refuses to get over her crush on you. As for HB9, just go to her place for now or stay out. You may even want to consider telling her about your roommate's tendencies. The housemates know, ask them what they could possibly do to help. I doubt they want to be stuck around this drama for a long time, either, because it will get very old very quickly.

Finally I have this: I believe she was absolutely wrong to say you had to "appreciate her feelings more." you have told her that there will never be any sort of relationship between you two. And it is unreasonable for you to put your social life on hold. In fact, I would think that if you were to do as she asked, she would misinterpret that as you caring about her because you would be doing something for her benefit. If she's gonna get over you, I think it may actually help for her to see you with other women. It won't be fun, but it never is fun to find out a person you have a crush on isn't interested at all. That being said, it's very necessary.

Thanks for the reply
Unfortunately I have done pretty much everything you listed! The reason I posted this was because I had just spoken to her to resolve it but feel like I'm going round in circles. I told her that there was no attraction at all and never would be. That is all it is too, a simple crush! I have never had any sexual contact with her. I said I have things that I want to be able to do and I cant just stop because someone tells me otherwise - I wont live to her rules (relationship rules without benefits).

I think I'm definitely going to tell the girl about this 'obsessor'. Best that she knows so she isn't caught off guard. As for staying at hers, my bed is so much better haha! Typical my choices are limited already!

Your last bit of advice though is absolute gold and I never saw it that way. I need to put her in an uncomfortable situation to be able to get over me. No more caring about her feelings after I pickup women and hopefully she will get the message! I think this might just work!

A girl telling you about her feelings bother you ?! really ?!!! i advise you to be a man, she can do nothing unless you want to make a big deal about it....

I live with her and am her friend. To make things worse, my bed is directly above her bedroom. I just don't know what she is capable of - its not just telling me her feelings, it is her being obsessed and telling me I need to make allowances for her and cried loads when I said nothing would happen (more than once in a seven month period). Your solution would typically work in usual situations but this isn't normal. As I said already, its an obsession - you don't know what girls like this are capable of, and she hasn't taken the hint already.