You don't just not have bipolar anymore. You can have stable periods and long ones at that but bipolar is a condition that doesn't go away, it is just managed.
If it's anywhere on her medical records that she has suffered mental health issues, it will have been discussed at her initial midwife appointment as they use it as a factor to determine a high or low risk person. Also, if she truly suffers with mental health, social services will see it because it's not something that you can control and switch on and off.
Agree with everyone else in that you need to have no contact with her. If she tri s to contact you via messages or calls, keep the evidence (call logs, texts etc) but call 101 and tell them that this person has a restraining order and is trying to contact you. Believe me, this will mean she is in the wrong. But if you respond, regardless of what you say (offering support, being nice etc) you'll end up in trouble as she could tell them you've said anything.
You need to focus on being the best person you can be. Stabilise your life in terms of living arrangements, job etc and prove that you can be a good dad. If you stay away from her and can prove that you can be an upstanding citizen for 9 months, that can only go for you.
Regardless of how you feel about her it sounds as if she is ruining your life. Focus on your daughter because this woman is toxic and she could cost you that relationship. You need to show everyone that you can care for your daughter and be prepared to do that.