Anxiety and some mood swings

Myself and my relationship partner had some issues that lasted quite a while. I was prepared to break up with them but they told me they'd commit suicide if we broke up, since they have been quite depressed and suicidal the whole time I've known them. I didn't want to continue the relationship but I couldn't bear the burden of having them take their own life because I wanted to move on from a relationship (they refused every alternative that I suggested to avoid suicide). When we finished talking that day I felt completely empty inside. Flashing forward a little bit, they seemed to expect everything to just fall back into place like nothing ever happened. But I was extremely upset and anxious because of school and more specifically them. I constantly went back and forth in my mind between "maybe it'll get better", "this is not what I want", and other thoughts. I'd either be completely distant and aloof, feel an overwhelming sense of guilt, be extremely irritable or be paranoid to the point of tears and mild panic attacks. I feared I'd begin to start resenting them and that's exactly what's started happening recently. I've become more distant towards them. They're hellbent on trying to "fix" things but I jump between not caring at all about them, completely hating them and just wanting to cry. More often I feel hatred, I feel like they're being selfish for only wanting things done their way, and soon after I feel guilty for thinking these things about a person with issues. All these conflicting feelings have just made me feel miserable or empty inside. I get anxiety from checking my messages, or opening Instagram for a few seconds, afraid they might realize I'm purposely ignoring them. I'm afraid to think about the situation too much because I get short panic attacks in succession and I don't want to start crying out of nowhere

Sorry for the long post