First of all, congratulations!
Everything your feeling is perfectly natural. Twins is a very daunting task for anyone. I really commend you on not wanting an abortion, too.
As much as it may suck to hear it, you may well have to end up leaving university. It depends on how you are able to juggle all the things in your life, and how much you can handle all at one time. As far as financial problems, start by looking around your community for places to go for support and help as far as getting things like food and basic supplies like car seats and cribs. There are resource centres that will give you either a voucher, or the actual item you need.
For everything else, start by taking a deep breath. Don't think about everything at once if you're feeling this overwhelmed. Focus on one thing at a time. For example, first you should talk to your family/friends and try to establish a strong support system. You will need it for the journey ahead of you. You should also talk to your boyfriend as well, and talk with him - as calmly as you can - about what is ahead for both of you. Ask him if he is going to be involved at all, and tell him to be brutally honest, even if it will hurt you. It's much better than having a facade for however many months and then one day he just disappears. Tell him exactly how you feel and what you eed/want from him and see if he will be able to handle it. Don't just dump it all on him, because he'll be overwhelmed and run. Take it slowly and focus on one thing at a time with him as well, and try to get through it together. Now, as far as not knowing how to handle a baby, or two babies, you should try looking into free prenatal and parenting classes, and looking into online resources for younger moms. Books can also be a great source of information and help, and you should see if there is a young mom support group type thing in your area. And of course, ensure you take prenatal vitamins with folic acid, eat right and get lots of rest and light exercise.
Now, I've got a few questions.
How long have you and your boyfriend been together?
Do you and/or him have a steady job?
Where are you each currently living?
I'd love to help you as much as possible, but I need a little more information, haha.