I think the feelings that you feel are normal. You spent some time with this man, emotionally invested in him and now he is no longer in your life and because of how he treated you there is lingering resentment. You seem very aware of what you’re feeling which I think is a good sign. The fact that you can see what you feel as ‘anger’ is important, and hopefully will not cause you do any more damage to yourself by externalizing the behaviour (sleeping with others, alcohol abuse etc).

Be kind to yourself and recognise that you’re mourning. Treat the physical sensations you are feeling. You say you have pain in your stomach is it possible to get a massuse to massage the area? Maybe light exercise such as yoga or swimming may help. Do you write, draw or paint? Failing that you could try a boxing class! Or it might be worthwhile to talk to a therapist or counsellor? Journal what you are feeling, maybe write an angry letter but do not send it to him. I had a whole week off during my last break up where I just cried. I read somewhere that the healing is in the aching.

It won’t help to see him again, an apology from a manipulative person means nothing, that’s if this person can even feel guilt, concentrate on your own wellbeing! Carry on with normal activities as much as you can, and try and eat and sleep well. I hope the pain goes away!