I'm going to neglect to help my girlfriend with her mental health issues in order to stop triggering my own mental health issues
Are you getting tired of having to help her?
Yes, I allegedly can't handle this and I really need to deal with it by myself
Normally it is not good to ignore people's problems but if it is harming you, it is okay to stop paying attention to others to help yourself. Once your doing better you can help others.
It won't help. I need to pull through this.
Realizing that you need to take care of yourself before you can help others is a very mature way to look at it. If you do not feel you can help your friend because you are having mental health issues as well, you without a doubt should spend time for you.