How do you deal with an absent father and stay positive during your pregnancy

The father of my child is one who says one thing and do another and I understand that but this is my first pregnancy and I didn't anticipate the emotional rollercoaster that I'm going on. I'm not one to cry but I have cried more in the past week then in my entire life. I'm trying to stay positive so this pregnancy stays positive but I keep having these emotionally breakdowns because he dose things like not return my call for a week or says he is going to show up and doesn't. Is it wrong for me to just stop communicating with the father so I can get through my pregnancy then deal with him after the baby is here? Or should I just bit the bullet and keep on the roller Coaster