I feel for you so deeply as you now try to meet the challenge of reforming yourself whilst facing the grief of the breakup.
The relationships we have in life tend to have an impact on our identity. We tend to identify our self through how we relate to others and the world in general. Eg: I am Andrew who is ____'s boyfriend. I am loved by ____. I am someone who goes to this place or that when I'm with ____. I mention the idea of reform because now you're looking at reforming your 'I am' to a degree, your identity (how you identify yourself). Now that you're not in a relationship with your partner, do you have any idea when it comes to who you want to be without your partner there to relate to? I don't expect you to answer but just to have a think about the idea. Dealing with the loss of an appointment (role we feel we were meant to play in life) is definitely a challenging disappointment. Consciously appointing our self new positive constructive roles is key when it comes to moving through grief of any kind.
People can tend to underestimate the impact of a breakup, on so many levels. Whilst age is never factor regarding the intensity (we all feel pain), mind, body and spirit are definitely all 'round factors. By the way, when I refer to 'spirit', I'm talking about our sense of connection to the world in a number of unique ways. It's not a religious thing.
The mental aspect not only relates to our identity, it also relates to how we process the information we're trying to come to terms with. Referencing old mental programs is a process which may not get us to where we need to be. Eg: I am of value because I am ____'s boyfriend. I am lovable because ____ loves me. Sometimes we need develop new mental programs which define our most authentic self.
Regarding the physical side of things, it's worth Googling 'The 4 chemicals for happiness '. Researching how to boost these chemicals within our body can be helpful when we're feeling an all time low.
Andrew, you can see how complex we are in regard to dealing with major challenge/change. I could say 'You'll be right, time heals' and all that stuff but I believe it's far more constructive to provide insight when it comes to consciously managing our way toward healing. Developing new mental programs in our head to identify with (mind), boosting the happiness chemistry within us (body) and creating new and positive connections in this world (spirit) are actions which aid in our reformation.