confused military mom

I'm 20 and a single mom of a 2y boy and a birthmom of a 4y girl who was adopted by my foster parents. Both children have the same father(21). He is in and out of my sons life. He averages 1 day a month for a couple hours if that. I have finally told him I was moving on and did not want to be with him any longer. I have joined the military and leaving for bootcamp in July. My sister(23) is going to move in with my mom becuase I gave her power of attorney. My mom works graveyard sift and my sister is a reg. 8-5. This is best because I live with my mom due to I'm going to college P/T at a community college, F/T at a private college, and do online classes. My son will have the same routine while I'm gone for 18wks. My mom is planning on visiting on the weekends while I'm in AIT (the last 9wks). When I return from bootcamp, 1 week before thanksgiving, I'm going to move in January 2006 for better job oppertunities and education. My mom is very excited for me because I'm trying to do whats best for my son and can become more independant from her. I have talked to my sons father about the whole situation (military and moving). He says he will miss me and still wants to be "friends because I'm his best friend" and fights with me about moving. He complains because he will not get to see his son. I keep telling him that he doesnt have much time to see him now and when I move it will be the same (I plan on coming back for family engagements, vacations, etc). Does anyone think that its not a positive situation for me to move or am I just being selfish? I dont want to take his son away but I dont like the violence in my city (my neighbor just got busted for a meth lab, kids in high school are stabing eachother with chiness swards, eduaction scores are low for the state compared to other states). Any openions would be greatly appreciated.