Reading The Explosive Child helped us a lot. Not only did I have a child with meltdowns, but I had students with them, and my son is currently 25 years old and no longer has meltdowns. It's been a long time since I read the book, but the biggest thing I remember that worked well was, either try to recognize the meltdown and create a distraction, or if they're in the meltdown, there's no option other than to wait it out until you can get the other side. @AzureRomeo

Btw, don't think TOO MUCH about the future. You'll drive yourself crazy and you can't foresee the progress that she'll make. One step at a time, one phase at time.

Coping came with prayer and reading the bible for me. I lean on God for strength.
But, down to the nitty-gritty...when my kiddos were diagnosed, I jumped head-long into therapy through our local Regional Center. I learned a lot. The most important thing you can do RIGHT NOW, is find the best therapy approach that works best for your particular child. Trust your instincts when it comes to therapy. Give them a chance. But don't let them go to long if your instincts are telling you to go in another direction. There are many approaches.
At this point, it won't do you any good to worry or be scared for her future (although it's perfectly natural). Children with ASD go through MANY stages. You can't look far into her future right now. It's just not possible. I have three children with Autism. So I know what I'm talking about.
How do you help your child? Be positive. Focus on her gifts and talents. Let her excel in those. It may take years before you discover what her gifts are...but she has them! Talk as simply as you can, not in long sentences (at first). Eventually (if not already) you will learn what she understands and what she doesn't. KEEP IT SIMPLE. The best things you can teach your child in the beginning is what "yes" and "no" mean. "all done" and "more" are good ones to establish as well. I'm here for you if you need anything. You're not alone!!

ABA has saved our life! Her behavioral analyst and assistant have helped us figure out what works best for our daughter. Some of the things we find most effective are chew toys and "wrapping". We have purchased many different teethers and sensory chew toys. When she is upset we offer these. The wrapping is the most effective. When she is in full on melt down mode we tell her its rollie time. Essentially we wrap her in a blanket tightly and apply pressure. It has helped so much!! After a year in aba she now can identify when she needs these techniques and asks for them!

Start with knowing that you are not alone! My son has had the same diagnosis. He has violent outbursts almost all day every day. How do you cope?
#1 Find a good doctor- ex: child psychiatrist
#2 Be open minded to the possibility of medications- no they aren't a cure but they can help ease her discomfort and yours so that therapy will be more effective.
#3 Try and stay patient and calm, she feeds off your energy and learns from your example. Take breaks when you need to. Lean on your support system and make sure you take time for yourself. If your not happy, she'll sense it. Take time to read a book, or watch 1/2 an hour of T.V. alone or take a bath something that helps you.
#4 Read- research- and breath You can do this!