Soldier... my best wishes to you in your trying situation. You seem to have your head on your shoulders, so I'd like to offer a little bit of advice.
Handguns are relatively simple, but learning to use them is actually very challenging and complex. Being relatively new to handguns, I was really surprised at just how much there is to know and master. That's one reason why you should really just get a shotgun (see tip #5). You are in a disturbingly dangerous situation, and that is why you and your dad should PLEASE take a introductory AND a tactical handgun course with a good instructor. I may have skipped this, but I don't seriously expect to ever have to use a gun for self defense (knock on wood). I don't ever want to shoot anybody, and it sounds like you don't either... good start.
That said, there is a lot of info you can glean from these boards, maybe other THR folks will give you some good links.
First, Jeff Coopers Four Rules of Gun Safety!
1. All guns are always loaded. Even if they are not, treat them as if they are.
2. Never let the muzzle cover anything you are not willing to destroy. (For those who insist that this particular gun is unloaded, see Rule 1.)
3. Keep your finger off the trigger till your sights are on the target. This is the Golden Rule. Its violation is directly responsible for about 60 percent of inadvertent discharges.
4. Identify your target, and what is behind it. Never shoot at anything that you have not positively identified.
Let me just say that I am no expert and my advice is well informed but lacking experience... that said here are my tips:
1. Practice... A LOT. Shoot 50 rounds a week if you can. Take slow careful shots and make that 50 rounds as educational as possible. While you're practicing, try different types of ammo. Some ammo doesn't feed well in some guns... especially Hollow Points. That means your gun could JAM in the heat of battle. Don't just buy a box of hollow points to keep at home without trying at least 100 at the range.
2. Be aware of penetration! Even 9mm bullets can go through lots of walls and hurt your family or neighbors. In fact, a Hollow Point 9mm bullet shot out of a handgun can penetrate 8 Pieces of drywall. That's no joke. It's also very possible that the bullet can pass through an attacker and zing into your neighbors house. Another reason to seriously consider pepper spray. Please look at
www.theboxotruth.com to learn about penetration.
3. Learn the Law about home defense with a firearm in your area. Find out exactly when lethal force is acceptable. Even if you shoot him in the knee cap, its still lethal force. Also, be aware that if you do have to use your gun for self defense, the police are probably going to confiscate it as evidence for a very long time... so you don't necessarily need the most expensive gun around.
4. Learn some basic first aid and get a good kit together. If someone does get hurt, you may only have seconds or minutes to respond. Do you know how to slow down massive bleeding or treat shock? This is a good thing to know about anyways, even if you never hear from your terrible family member again.
5. Consider getting a shotgun with 00 Buck Shot (NOT BIRD SHOT!) Handguns are less than ideal for home defense. They are more useful for concealing or for fighting your way to your long gun.
6. Study the layout of your house and figure out what the most defensible position is and where the safest backdrops to shoot at are (god forbid). If said attacker does invade your house, the best thing to do is probably hole up in the safest room with your gun pointed at the locked door while your cell phone is dialing the police. You DO have a cell phone, right?
7. Like another poster said, get a big dog! Also, you could get an alarm system.
As for other tips, I think they should be specific to your tactical situation. What kind of neighborhood are you living in? Is it urban, suburban, rural? How far are you from your neighbors? What is your house constructed of?
How long does it take for the cops to arrive? What kind of pepper spray do you have? Can you set up this GPS tracker thingy to set off an alarm if he gets close?
Thats it for now....