Looking for some help with this. Thanks in advance

I’m in a lesbian relationship and my girlfriend has Anxiety, depression and bipolar disorder. This morning we were listening to the radio. They usually have a lot of topics to discuss and we discuss them to each other as well. In doing so I ended up getting frustrated. She saw and felt me getting frustrated and asked me why I was getting frustrated. I said idk and I don’t want to talk about this anymore. When I did this she immediately gets overwhelmed. Here is some history. I’m use to not talking about my feelings. In any relationship my feelings, opinions and thoughts become irrelevant or they get listened too but invalidated. This happened to me a lot when I was a kid with my mom. Me and my mom would talk about stuff and I would give my opinion and she had a way of convincing me that what she is saying is true/right. So then later on in life I stopped giving my opinion and just ask for other people to give em there’s because now idk. I never know and never have an opinion or thought. So when she asked me why I never know what to tell her because I don’t think anything I just have feelings and don’t want to deal with them. If anything I just want to feeling them and not talk about them. As for my girlfriend she gets overwhelmed when I don’t want to talk about how I feel. It also causes her to become depressed. The problem is I’ve been giving in and talking about my feelings because she wants me too. Not because I want too. I’ve been going to therapy so I know it’s right to figure out why we feel the way we feel but sometimes I feel like everything isn’t ment to be talked about, figured out or whatever. She feels like this subject is serious because I need to find the underlying reason and I’m like it’s not. I get frustrated for no reason, It’s me let’s drop it. She can’t just let stuff go. I know her anxiety and depression has a lot to do with this but what am I suppose to do? How do I not get frustrated because her anxiety and depression has set in? Or am I suppose to just talk about it because it’s the right thing to do?