Resenting baby's dad

I am just wondering if anyone can relate to my circumstances.

I resent my partner and do not feel the same about him anymore because of how he is with our baby.  He runs his own business and is out of the house from 6ish to 5ish Monday to Friday.  The first thing he does when coming through the door each evening is to open his laptop.  4 nights per week he is out exercising so he sees our son awake for about 20 minutes each evening.  He has his other children to tea 1 night per week so our son doesn't get a look in and they also stay for the weekend every other weekend and then our son doesn't really get a look in.  On the weekends that he doesn't have his other children he is out of the house for 1 day exercising.  On the occasions that he is home he is usually surfing the internet on his laptop, chatting to anyone who is available on his phone or looking for something to do other than be with his son.  He has never taken him for a walk alone.  He has actually only been with me a handful of times and that is under duress!  When i have confronted him he claims not to do this on purpose and says he loves us but in my opinion actions speak louder than words and his actions are saying to me "I CAN'T BE BOTHERED".  His life has not changed in the slightest and i think it is only a matter of time before i get really sick and tired.  The mother of his other children left him for another man and when i have kicked off in the past he once told me that she used to have similar complaints to mine, with the exception of ignoring his children.  He has always been a hands on dad with his other children and will do anything for them,, shame he can't put himself out for our son.