Hello and welcome. I am sorry you are having a difficult time and I hope we can help you.
May I ask a few questions? Why do you think you have PTSD? This is something that happens when you have had a very bad experience such as a war, assault, accident, disaster and the memory of it keeps returning. I understand you feel bad about pushing your boyfriend away and you regret doing this. It makes you sad you acted like this. As you say, songs etc can remind you of the good times you had with your boyfriend and it's natural to feel sad because you are no longer together. Beyondblue has information on PTSD which you may find useful. Copy this link into your search engine and read about it. https://www.beyondblue.org.au/the-facts/anxiety/types-of-anxiety/ptsd
It puzzles me a little why you pushed your BF away again after you mended the relationship. However you did this and now feel upset. I think it would be a good idea to see your GP and have a good chat. If you do have PTSD then your GP can refer you to a psychologist. In any case it would be helpful if you can sort out what is going on in your life and get some help. Ask for a long consultation with your GP.
Feeling numb is not good but often is part of a relationship break up. How long have you felt like this? Again you need to talk about this with your GP. There is a great difference between feeling sad because of the break up and having PTSD. I suggest you get this part worked out soon and your GP can help with that.
Please continue to write in here as often as you wish. It can help to talk about your feeling and why you feel sad. We are not mental health experts. We can talk from our own experiences but we cannot diagnose what is happening in your life. This is why it's important that you get expert diagnosis and treatment.
Please keep in touch and let us know what's happening in your life.