Yes, I would be calling the surgery first thing in the morning and speaking to the Practice Manager to arrange an appointment at a suitable time for you tomorrow to discuss "a complaint regarding a serious GDPR breach from your surgery". YADNBU, I'd be furious and terrified, in equal measure.
Most importantly, you need to focus on your DD and how she's feeling.
I was 15 when my Mum had what the Doctors told me was called a nervous breakdown and first tried to kill herself (to me, it felt entirely 'out of the blue' - but then I was 15 and wasn't particularly interested in anything apart from my friends and boyfriend). It was a huge shock and she ended up spending over a year in a secure psychiatric unit - where she attempted to kill herself on at least 3 more occasions. So, I faced a similar revelation about my own Mum's mental health at the same age as your own DD, and these are a few things I think would have helped me at the time. You'll know which (if any) may be suitable for your DD. I also have 2 DDs myself (aged 9 & 11) and have explained my Mum's Bi-Polar disorder to them and continue to talk about it and answer questions when they have them.
I wish someone had a conversation with me, and using basic, straightforward, unambiguous language, explained what a 'nervous breakdown', or a 'mental health issue' was - it was years before I understood that it didn't mean that she was 'mad' (as in bonkers, a total fruit loop) and that she hadn't been merrily going about her life when suddenly, it felt like 'her own internal engine' had broken down and she simply couldn't keep going.
I would encourage your DD to ask questions. I would be telling her that she could ask anything she felt she wanted/needed to, and I would reassure her that I would be honest with her - and then I'd be honest with her.
I would reassure her about how your mental health is these days. It sounds, from your OP that you went through a horrible time, but that your mental health is now under control and that you sought help and continue to use the services that are available to you (you mentioned seeing a psychologist - does this still happen?) Talk to her about medication you take and how it affects you. Find a common language you can both use to discuss how you are feeling now compared to how you felt back when you were really poorly e.g. I was feeling about 2/10 on the happiness scale in summer 2014 (or whenever it was), compared to the day you were born which was 10/10, a normal, dull day at work would rate a 6/10, then the day I lost my purse, my car got broken into and I was sacked from my job was 3/10, but on the way home I bought a scratch card and won £100,000 so it ended up a 9/10! This gives you both an easy way to communicate about your mental health (tell her she's welcome to ask "How are you doing out of 10 today?" whenever she likes), you can ask her too, which will help you to keep an eye on how this is all affecting her. It will help her to be able to get that quick burst of reassurance from you that she will need, without having to get into a looooong, deep and meaningful conversation every time.
Reassurance is really important and she’s going to need lots of it. In my experience, my main concern was that my Mum was going to try and kill herself again and that next time, she would succeed. As difficult as it might be for you to talk about that time, your DD will need to hear how differently you feel now in comparison with how you felt when you tried to take your own life (and therefore, logic dictates how much less likely you are to attempt suicide now). She needs to hear from you that you are not feeling suicidal any more, and that you are aware of the signs that you are going downhill and that you have things in place (a CPN, your Psychologist, contact numbers for emergency mental health services etc.?) which you can access quickly and easily, as soon as you recognise them. Talk to your daughter about these signs so that she can learn to recognise them in you herself, which will help her to feel that she has a small way in which she can contribute to keeping you well and it gives her a sense of control, which she will be lacking in this situation, which will, in turn, help her to feel better. Make a list of the contact details for the services you use (be sure to include ‘numbers to call in a mental health emergency’), stick it on your fridge/ notice board, let her know where it is, and what to do if X happens, if y happens etc.
Be honest with your daughter. She will be feeling confused because part of her will probably be angry with you (I remember thinking “Cheers then Mum, I’m not good enough to want to stick around for” and “Thanks for thinking of how shitty and hard my life would be if you’d killed yourself, you’re so selfish!”), she may have lost some trust in you too (I felt scared around my Mum for years - for example, if she was driving me, I would worry that she’d suddenly swerve into oncoming traffic to try to kill herself and I’d die too) and your DD now has ‘proof’ that her Mum isn’t always truthful (I found it hard to marry my hard working, confident Mum from before she got ill with the frail, zombie-like woman, who appeared to have aged 15 years almost overnight and who spent her days sneaking around the house, ‘popping to the shops for milk’ but actually buying lengths of hosepipe and duct tape, along with pack after pack of paracetamol, finding excuses to use Dad’s car as his key-ring had the key to the locked bathroom medicine cabinet on it and planning how to kill herself). I’m sure it’s really hard to talk about when you were so unwell, particularly with your own DD, but if you lie at this stage, then that trust will only break down further. You only have one chance to give her this information for the first time and if you lie to her now and she finds out later, it may have devastating consequences for your relationship with your DD. There may well be things (particular details of exactly how or where you were planning to commit suicide for example), which you may not want to share, or you may feel that she’s not mature enough to handle that level of detail yet. It’s completely fine not to share these details if you prefer, but do be honest with her about it; it’s better to hear “I’m sorry sweetheart, but I’m not ready to talk about that yet/ I’d really rather not share that bit with you, as I am ashamed about x, y and z” than for you to lie to her, and for her to find out the truth 6 months/ 10 years down the line. She may not feel able to forgive you for lying in relation to such a life-altering event (for both of you).
Your DD may become slightly overprotective towards you or she may go in completely the opposite direction and start to behave a little ‘immaturely’ and appear to want to be protected by you. You may even get a little of each! She will be confused by these feelings (I’m sure it’s pretty obvious to you why she might be feeling this way), so I’d give her exactly what she needs in terms of spending as much time as she wants with you (insofar as you are able) and giving her as much physical contact as she needs.
So, the basic ‘headlines’ from the ma-hoo-sive essay I appear to have written (sorry OP, and well done if you’ve read this far!):
Tell her ‘your story’
Encourage her to ask questions - It’s OK if you don’t want to answer all of them, but be truthful
Reassure, reassure, reassure!
Always be honest
Find a way to ‘check in’ with how the other is feeling
Give her some ‘control’ by letting your DD help you
Loads of contact, time and psychical
I’m so sorry that this has been such a jarring, unsettling experience for you both. You sound like a lovely Mum who really cares about her daughter, so I hope very much that one or two of the things I’ve said might help a little. Fingers crossed that everything seems a little brighter in the morning – I always like ‘This too shall pass’. Give them hell at the surgery, wishing you the very best of luck in dealing with that bunch of incompetent numpties!