She is cutting?  Does her father know that?  I am guessing he got angry because he got scared.  Having someone commit suicide "on your watch" could not have been easy and, while that was certainly not the most productive reaction to hearing that his daughter was having depression issues, is understandable.  Perhaps you could speak to the guidance counselor and ask her to speak to the father again.  She may not be able to talk to you under confidentiality laws because you are not the mother but that does not prevent her from listening to what you have to say.  That does not breach anything.  Your boyfriend may not like the idea that his daughter has anything that reminds him of her mother but he needs to deal with this.

What?! Your boyfriend is an idiot. She's at much higher risk of depression and suicide given her mother's issues, why would he not want to prevent that?

I'd have it out with him, he's being stupid.

Your boyfriend is an utter idiot. As tog says, this girl is a prime candidate for a host of mental health issues. 

If you want to help the girl, have a come to jeebus with the father. Ask him if he wants his daughter to end up the way her mother did. It sounds as if he could use some therapy, too.

She May have a mental illness from her mother.  She must be seen by a professional mental health person like an MD. To get some insight on what’s going on. That the first step 

Maybe if she went back to her counsellor and told her/him about the cutting and her father's refusal for her to see a therapist, the counsellor would be the one to call CPS.

This is sad beyond words.  You have a child crying for help and her father won't get it for her?  Your boyfriend is an insensitive idiot.  What is his opposition to his daughter getting help?  Have you discussed this with him?  Gone to the mat with him over it?  With a family history of mental illness and a mother who committed suicide, it is beyond negligent to not get help for a teenager who is cutting and has asked for a therapist.

Does her school have a social worker or a psychologist on staff (as opposed to just the guidance counselor)?  All of the public schools I attended did, and you didn't need a parent's permission to speak with them.  If they talk to her and think she needs help and learn that her dad won't get her treatment, they'll probably report it.  In the meantime, it's someone to talk to.  Is she due for a visit with her pediatrician?  If so, get her in there ASAP and make sure he's aware of what's going on.  Her doctor may not be able to tell you anything about her, but I'm not aware of any laws that preclude you from giving him information.  Maybe he can help. My county has a health and human services department.  They have mental health professionals on staff.  You may want to find the equivalent in your area and give them a call to ask for advice and resources.  They should be able to steer you in the right direction.

This would be a hill to die on for me.  This girl may not be related to you, but you've raised her as a daughter and if anything happens to her you will be devastated.  I'm sure you're deeply affected just by seeing her suffer on the daily.  Push your boyfriend.  Let him know that this is important to you and that you can't sit by and watch the girl suffer.  Frankly, I don't know how you can have any love or respect for this man after seeing how he reacted to his daughter's cry for help.  I can maybe understand him being annoyed if she's a drama queen who is always pulling stuff like this, but it doesn't sound like that's the case.  Push him.

I am so disappointed in your BF.  His concern should be his daughter and getting her taken care, making sure she is healthy and DOES NOT follow in her mothers life.

If he wont sign off on therapy she can always go a Church and speak to someone for free without parental consent.  The scariest part of this, is this poor child knows she needs to speak to someone and hes being a douchebag.  Yelling at her for this is not helping her in any way but instead it can alienate her and make matters worse.  

I am praying for her and hoping that he comes to his senses about the welfare of his girl.

Daughter.

no wonder she went to her school consellor for this as she doesn’t feel she has an approachable channel at home to discuss or vent things.

i mean take for example husband and wife stressed with work and kids, often we vent to one another what a terribly shit day its been.

now this daughter is in a dark place and dealing with emotional stuff too and she has no-one at home to go to for venting. That must make her incredibly lonely. 

You need to speak to your partner and explain things this way that he can’t act all macho like she’s weak etc. Its amazing she is a gifted kid excelling in academics at school and she has the opportunity to go real far. It must be awkward already being in a grade where you are a year younger than everyone else and feeling out of touch with everyone.

your partner needs to see as a parent he must be approachable and supportive and currently he isn’t 

are you in a position when her dad isn’t home to sit with her casually in a friendly supportive manner and ask how things are in her life and school and let her know if she ever needs to vent or discuss something bothering or upsetting her that you are always there to support her.

she needs to know there are people who care

often those depressed and committing suicide feel they have noone even though family are there, we just don’t see the warning signs

What the hell is wrong with people? You know that this poor girl is cutting herself and you aren’t getting her any help? If dad won’t get this kid some help then I hope you do the right thing and call child protective services. Suicide and depression run in the family. Do you want this kid to kill herself? Sick