For me, sometimes I can feel the delusions setting in and know that the thoughts are out there, but once they are full on, there's no going back - they are all too real. In the midst of them, they are just legitimate thoughts and feelings and nobody can tell me that they aren't real because they just feel real. Nothing but time (for me) or meds can change that.

As for hypo/mania, people w/ BPI still get hypo, we just also have manic episodes on top of that. It only takes one manic episode to dx BPI. As for telling the difference, I believe my diagnosis came from the fact that I get delusional when manic, not when depressed whereas people with BPII get psychotic when depressed, not when they go up and so far as I know they are more likely to diagnose somebody as BPI if they get psychotic while up as opposed to down (but I am not a doctor, so you should bring this up with your doctor). Also, hypo will leave you with more energy and needing less sleep for a while, but mania will really wreck your sleeping patterns and derail you for longer than hypomania. Hypo is all like, you're more energetic or agitated, but mania is all like, super energetic/agitated and/or angry.

Hypomania can be needing less sleep for a few days (I believe the DSM says 4 days or more) but mania will leave you running on little to no seep for at least a week or two, though many, many times longer than that. For example: when I was 23, I stayed up all night for months, surviving off of short power naps during the day because I thought if I went to sleep (at night), space aliens would kidnap me in my sleep. (Though this is not to say that hypo cannot last longer, certainly it can, it's just not as intense and so far as I know, in BPII, the depressions are more intense, longer and some/many times psychotic.)

Were your delusions when you were depressed or when you were feeling "better"?