Broke up with him but might be pregnant

I broke up with my boyfriend a week ago because things just weren't going to work out longterm. He's (mostly) nice, we just want very different things from life. In the stress of the breakup/visiting my parents for the holidays/juggling things from work, I didn't notice that my period was late until today... and it's over a week late. What do I do if I'm pregnant? I want children, but I'm not where I need to be in my job yet to support a family. Also.. what do I say to my ex? If I decide I can't keep it, do I tell him at all? If I do keep it, does that mean I should get back with him?