Well, it is your responsibility to manage your mental illness, and to not get blackout drunk and do things you don't remember doing, like sleeping with other people. So I won't sugar coat this, because it is important that you grasp the gravity in order to motivate yourself to get better. You need to get tested for STDs out of respect for your partner, don't put her at risk, get tested and make sure you have not caught anything from the lady in the tent. And then it's time to get on a proper medication and possibly some therapy so you can work towards preventing this sort of thing. Stuff like this happens to a lot of people with bipolar disorder, and a lot of us go through tough learning experiences / life lessons along the way. It is not your fault that you have bipolar disorder, but it is your responsibility to manage it to the best of your ability. It is best to learn from this and allow it to be a wake up call for you, time to get serious about treatment.