First, give yourself permission to nurse anywhere and everywhere you and your family may want to go. There is nowhere that is off limits. Don't feel like you have to find a private place or that you have to nurse in a bathroom. Just buy a cover-up and practice nursing discreetly. I know people have horror stories about people berating them for this, but in the 2 years I nursed (2 kids), I never got anything but compliments about what a gift I am giving my kids. The only place I did not nurse was the church pews (I went to the nursery). If anyone does make snide comments, and you don't feel up to the confrontation, then just ignore them... they will go away.
As for nursing at home, I found a couple things helpful.
*First, nurse when you get the chance even if baby isn't asking. If your older one is occupied eating lunch, nurse. If your older one is entranced by a tv show, take advantage of the time.
*The second thing is to make a basket of toys that is ONLY for while you are nursing.
*Third, let him help. While you are feeding, ask him to go fetch a diaper, wipes, a blanket, a drink for you, whatever. Older siblings love to feel like they are invaluable to you. I sometimes acted like I didn't know why my baby was crying. My daughter would tell me she is probably hungry. I would feed her, and my daughter would be so proud that I needed her and she allowed me to nurse in peace because it was her idea.
*Be sure to tell your baby sometimes "mommy is busy with your older brother right now and you will have to wait your turn". No baby has suffered any harm from crying for a minute or two, but saying this in front of your son will make him feel like it is more fair when you repeat that line to him while you nurse.
*Buy a ton of little surprises and wrap them all separately. Put them all in a basket. When you are nursing and he is getting restless, send him to get one and it will keep him busy for at least 10 minutes. (ie dollar tree toys, books, coloring pages, snacks)
*Last, before you plan to sit down to nurse, tell him that his sister is hungry and you need to feed her. Ask him if there is anything he needs from you before you sit down.
Eventually, nursing will get less frequent and your son will get used to it.