@Kchew22,
You've chosen to be in a relationship with someone who has mental health problems. You are going to need to get some support for yourself around this. If possible, get her to take you to an appointment with her mental health counsellor so you can get a referral for yourself (and maybe some advice from her counsellor).
Document everything. Everything.
You need to be prepared in case there is a time you need to assume custody of the new child. Document. Record. Diary.