What Can I Do about Deadbeat Dad and His Childish Girlfriend?

My daughter is 3 her father has basically been a deabeat coming in her life when he pleases doesnt acknowledge her on her birthday,holidays and so forth he has NO type of respect for me to make matters worse he has a 42 year old very unnattractive girlfriend who is childish she is always in my business thanks to him she leaves disrespectful headlines on myspace and away messages on aol directed to me. Basically online bullshit for awhile now she never says it to my face I TRY to ignore her.They recently had a baby boy she rubs in my face that he has a son along with the fact her son has both parents mind you this is supposed to be an "older woman" im 27 I feel so much hatred towards them I try to move on im a single parent i do my best but i have to deal with the fact he is over there everyday being a father to his son yet his daughter doesnt get a phone call The courts let him get away with NOW paying a small amount of support How can i release my resentment i cant deal with these ppl