Dear trusttheflow!
Thank you for your great advice, you are giving me lots of hope and it made some things clearer to me. I am seeing a counselor (only saw her this morning after she was on holidays), and I successfully battled panic attacks in the past.
This time, although it seems so obvious – I just did not recognise that it is basically the same as a panic attack, just as you said, and that means I know that I will find a way to handle it and I can separate my strong reaction from what is actually going on in our relationship! Your post was an important part for me to recognise this.

I have already written down all the triggers, all the fears that are related to it, and I am going to dissect and look and accept this shit until it dissolves 🙂
(Just after doing this I got a message from him, which I felt was lacking emotion, and I was able to write down each and every thought that went through my mind – from shame to anger – and finally understood how I went in to that state of panic! I really hope this is the way out…)

It should not matter how the relationship itself works out, I need to be able to deal with my fears, otherwise it will happen again in the next relationship…

Thank you very much again! Especially for the last sentence, it rings so true!