Please can i have some advice

Hi all, please can some people give me some advice or opinions? I have resently split with my partner an for the last 2years he has brought my son up as his own an just before the split found out im pregnant with his first child (after 5 miscarriages last year) an now he doesnt want any contract with my son after tellin him he would stay in touch an still hang out my son still looks up to him but my now ex wint have any contact with me other than for his unborn baby an i bein harsh in not wanting him to have anything to do with the pregnancy/baby because of what hes done to my son?