How do I deal with my bipolar father?

This is kind of long, but I’m not sure how to deal with this so it would be incredibly helpful if you could just take the time to hear me out.

My father is bipolar, we didn’t even know until about 7–8 years ago. We’ve had our ups and downs with him but he’s been managing his bipolar with meds and therapy for some time now. Except for one major hiccup that didn’t involve me, eveything has remained fairly normal since he was diagnosed. I love my father dearly, we’ve just never had an incredibly normal relationship since my parents split. Our conversations are usually about sports, science, TV, etc. things like that, and tend to be quite superficial. We have never been very intimate and open about how we feel about things. That is why my situation is so odd.

A couple of months ago, my father texted me (my parents are divorced) about 3 AM telling me how he’s incredibly sorry we don’t hangout enough, and that we should hangout before it’s too late. This scared the hell out of me because of that last part. I decided to be open with him, I told him I would really like that and we should make a serious effort to do that. I couldn’t sleep that night because I was seriously worried about him. About a week after that incident, he came over to my house to pickup my little brother for the weekend, like usual. He apparently also contacted my 11 year old brother saying similar things. My brother didn’t know how to deal with it, so he told my mom. When my father arrived to get my brother, my mom asked him why he was acting so oddly. He just said he was off his meds and became really depressed. That was the end of it, I never heard anything about it for a few months and our relationship went on as it always had and nothing had changed.

Tonight, he texted me again. He asked me if I would even care if he was around anymore. He told me he doesn’t feel loved, respected, or even needed. I know this is him off the meds, but I can’t help but be incredibly worried. I have no idea how to deal with this, and I don’t want to say the wrong thing because it’s really serious.

I’ve never been a very open person. I have a difficult time sharing how I feel, I’d rather keep my feelings inside and look strong to everyone around me. That is why I’m asking for help here, because I feel I will get genuine advice on how I can approach this situation.