Yes, you need to eat better and at least try walking. You should also go to your doctor to ensure there is nothing physical causing you to gain weight at such a fast pace.
The more you stress yourself out about your weight, the more you will cave on the junk. And it's not bad to eat junk food, just do it in moderation. If you want mcdonald's, get mcdonald's but don't order the double QP supersized meal (my personal favorite) get a kids meal or something on the dollar menu. Volunteer to do some of the cooking at home and make healthy meals when you do make roasted potatos instead of mashed, etc. Also, take some time to work out, start slow, go walking even if it's just a mile or a half mile at a time, be concious of what you eat, talk to a nutritionist who can give you some ideas on how to eat right.
I come from a family of people who have done crazy things because they hate the way they look. Trust me when I say that, if you don't give yourself a break, it will get worse and one day, you will wake up and be 60 and desperate (like my mom and step-mom and all my aunts)...and you don't want that.
My suggestion is to just try to be healthy as much as possible. And understand that healthy doesn't always mean thin. And cut yourself some slack, you will never look the way you looked in high school...no one ever does, and that's okay. You've gone through some pretty big life changes this past year, its bound to be stressful. Focus on being the best person you can possibly be and everything else will fall into place. It may go slow and it may take a while, but you WILL get there, if you want to.
Living with your in laws just kinda does that! I lived with mine for 2 yrs and gained 20lbs!! as soon as i moved out and saw oh much i weighed i nagged and nagged till my DH got me a WII fit , i got started doing that and the 10 min jump start cardio from spark people and the weight started falling off!! I would say its NOT normal to gain that much in 1 yr unless you have a medical condition do you have any that you know of? If not and you dont plan on moving soon then start working out lil by lil like i mentioned the vids. from spark people are 10 mins and really get you going!! Do you know about how many calories you are consuming each day? If not again spark people is free and you make a journal!! This helped me in the beginning as well!! im a junk food addict and fast food addict i do my best to cut corner wherever i can to eliminate calories but i still eat what i want but stay around the recommended 1200 a day!! You can do it just start small and work your way up!!!
I have to add....that as I keep gaining I'm getting more and more uncomfortable in my own skin and get closer and closer to wanting to just stop eating. though I know I couldn't do that in a million years. it just gives you a better picture of how I feel about this :(