I agree with Max. You need to be a happy dad for your little guy when you do see him so be proactive in getting over the breakup and accepting. If you're too reluctant to go to group counceling or something like Parents without Partners then try reading the 5 Stages of Grief. It's geared towards bereavement from losing someone to death but it still very much applies to what we go through when we are missing someone we loved due to a breakup.
“The willingness to accept responsibility for one’s own life is the source from which self-respect springs.” ~Joan Didion