I made a mistake, parents are being unsupportive?

Hi everyone,

In October last year I started a new job working somewhere I've been in close contact with for many years as my mum has worked there since I was born. It's a really close-knit company, and everybody looks after each other like family so I've known most of the employees since I was a baby, and I've grown up with them.
Before I started there, I was out as Bisexual to my friends and one of my cousins, and none of my family knew, as I had kept it a secret for about 4 years as I was still figuring out my sexuality and I hadn't been in a real relationship with another woman before so I wasn't sure, though I knew I was definitely somewhat gay. Around late November/early December I took a liking to somebody who I work with who I've met previously in the past (obviously because my mum knows her and has worked with her for many years) and she reciprocated so we began seeing each other (very low-key) and all the while I kept attempting to tell my mum about us, but I couldn't bring myself to do it. My mum had never expressed a real opinion on what she'd think of me if I was gay or how supportive she would be, but as we don't talk about topics like that I was especially cautious. My dad, on the other hand, encouraged me to be gay before he knew I was. Anybody who's come out to their family knows how nerve-wracking it is though. I just couldn't do it.
Most of my fellow co-workers became aware of our relationship and agreed to keep it a secret until I had gotten the courage to tell my mum myself, however a co-worker I hadn't really spoken to before discovered the relationship and was told to keep it a secret, and still went against my wishes and 'accidentally' blurted it out to my mum, who was distraught that I didn't tell her and that she found it out through somebody else. Of course, I tried explaining that I was attempting to tell her soon but I was too afraid too, not by any fault of hers, but she was too distraught to listen. My dad was initially thrilled when he found out I was dating another girl, but soon became incredibly unsupportive when he discovered how my mum had found out. It didn't help the situation at all that I told them how long I had been Bisexual for to reassure them that my girlfriend didn't pressure me into being the way that I am and that it wasn't a new thing, as now they believe that I am just a compulsive liar and that they must be 'bad parents' if I couldn't tell them who I was, even though they don't seem to comprehend that it's a normal thing for some gay people to not come out for years, for many reasons.
Since this happening, my mum has adjusted slightly and actually talks to me like she used to but still tells me every now and again that she hopes it's just a phase that i'll grow out of and she still changes the subject when I bring up my girlfriend, though this was nearly 4 months ago and it's become apparent to them that I'm not going to split up with her anytime soon. My mum has persistently told me that it's my life and that I'm free to do as I please because she can't stop me or change who I am, which in some cases I'm grateful for, but it still hurts that I cannot bring up my girlfriend without avoiding the awkward silence that follows.
My dad, on the other hand, has pretty much disowned me completely. He refuses to speak to me, hurls abuse at me whenever he can (such as- I'm a disappointment, he absolutely hates me, he wouldn't care if he never saw me again, he'll never forgive me), says he 'doesn't know who I am anymore because I'm a different person', and calls my girlfriend a series of horrid names and refuses to let her come to our house or let me go to her house. His persistent verbal abuse has caused an even bigger rift in his marriage with my mum (which has been spanning over many years), which he blames me completely for.
He is the only one in my family who seems to have a real problem with my sexuality, whereas most of my other family besides my mum have been incredibly supportive. I've been told to ignore his pathetic comments, but as you understand it's slightly more difficult to do that when he's my parent and I have to live at home with him as I'm not financially secure enough yet to support myself and to move out.
Another factor in this is that my girlfriend is a few years older than me (I'm 19 and she's 22) and she's a very out Lesbian who has had many relationships in the past and is more experienced, whereas I'm 'new' to the scene and I haven't had many relationships, and most of mine have been with men and this the longest and closest relationship I've ever had with somebody, and I have little experience. All of this has only added to my parent's disapproval. My mum's discovery of our relationship and the fact that she's known my girlfriend for many years before I met her when she was around the same age as me has also fuelled this.
Since beginning the relationship and trying new experiences, I have found the answers to a lot of questions I've been asking myself for years about my sexuality and discovered that I feel much more comfortable being in a relationship with another woman and that it feels right to do so, so I have since come out to her and to a couple of friends as a Lesbian, which I'm still adjusting to myself. I haven't told my parents this, and I don't really intend to anytime soon, especially as I feel it isn't necessary to do so if they figure it out if I continue having relationships with girls only and until I am 100% certain that I am a Lesbian.
I have well and truly accepted that it was wrong to keep my sexuality from my parents for so long and that my mum shouldn't have had to find out this through somebody else rather than me, and I have paid the price for this a million times.

My questions to you guys are....
How would you suggest I cope with my parents (my dad in particular) and keep up hope that they might come around eventually? I'm finding it incredibly hard to keep up hope in lately and it's getting me down a lot. Did your parents react the same, and if so how did you cope with it and how are they now? I could really just do with some support.