So I have been sending some photos to some very close cisgender female friends of mine over the last 2 weeks or so of my new clothes and shoes, etc.
However last night I forgot to delete them and my brother found them and told my mum they didn't really know what to make of it but as my new heels came this morning and my mum heard me walking about in them my brother came up stairs and said "we know" so I went downstairs I wrote what I was feeling and who I really am, then I said "I don't know how I'm going to tell Albany(My Cisgender Girlfriend)" and which my mum said "Just tell her it isn't working out" I have already dropped a hint to her and she said "I couldn't deal with my boyfriend being a girl"

Soooo my question is do I tell her the truth which she might not be able to handle, or do I lie to her and just tell her it isn't working out anymore?

*Edit* Also I hate her family they treat her like crap, and the other day I threatened them and she got really mardy about it saying I should just leave it alone, but I'm not that type of person, could I say it's her family why I can't stay with her...because I do bloody detest them

I would have to say honesty is the best policy. If you love your GF and want to prove to her that you mean to be in a trusting relationship, then you should tell her this other facet of your personality.

Lying will only mean at some point eventually the truth may come out. Would it be when you are engaged, when you are married, when she suspects you are having an affair, when you have your first child... ? You need to ask yourself how long would you feel comfortable to carry this lie on for, if you choose to lie.

Hmm.. Make sure she doesn't feel like it's her fault.
Talk to her, be honest. If she likes her family, it might upset her if you break up with her because of that
You have to stay true to yourself
good luck!

Personally, I'd suggest having a talk with her and being honest. If a break-up is in the cards it's probably better now than later.

Also personally, I'd be royally pissed off at anyone (parent or not, supportive or not) who took it upon themselves to 'drop hints' to other people.

If you feel that your personal safety wouldn't be compromised by telling her and that it isn't likely to spiral into negative ramifications for you then I think I'd suggest telling her the truth. While it may hurt her, I'd hope it's an option that allows parting on solid grounds and avoids the type of nebulous end that might lead to you each having regret or blaming yourselves later on.
No matter what you decide, good luck with it and I hope it yields the best outcome for you both.

As an aside, may I ask how old your brother is if it isn't intrusive? Personally, if somebody that had reached maturity went through my photos then told somebody else about them without considering the massive risk of harm then I'd be a tad peeved.

Tell her the truth. You could seriously mess her up in thinking it's something about her if you just say something as vague as "It's just not working out".

Reminds me of a girlfriend I had right after I started college. She was a gorgeous redhead and we were incredibly great friends. When we started getting physical it just wasn't doing anything for me. Of course, I still didn't understand my gender issues at the time. I was so frustrated with how empty our make out sessions felt. In the end I broke it off with her saying that while I enjoyed our friendship I just didn't have any feelings of attraction for her, there wasn't a connection.

Well, she took it as me saying she wasn't attractive and ended up dating about 10 guys in quick succession to prove to herself that she was. I felt awful when I later spoke to her about how she took it. As we talked she said she understood then what I really meant, but yeah, I could have communicated it better.

So yeah, don't do something stupid like I did. You know why it's not working out. Make sure she knows it's not because of her.

I would have to say, if you need to lie, lie. If you feel guilt will get to you, then tell the truth. My advice like how another member said it was to be true to yourself. Also, make sure your safety and secretness are not comprimised, just in case she wants to spread rumours about you if you do tell the truth. I do not know the dynamics of the relationship, but I can tell you she can tell your other friends if she has that personality type.

Tell her the truth but be gentle and positive about it.

It depends. If you are not fully out to everyone and don't wish to be right now, then it might be in your best interests to go with what your mom told you.  You can't be sure how she will react and if she may decide to out you to everyone in retaliation without regard for what it could do to you.