Hey there!
First of all, just take a deep breath and stop freaking out for a moment.
Believe it or not, tons of other people have been in the same situation as you and if they made it, then so can you.
I would recommend seeing Sally Willams ASAP. If you can make an appointment in person that would be to your benefit. If you were to describe the circumstances then maybe she might be able to offer some advice you haven't heard yet.
I might be mistaken but I think first year summer school averages for Engineering will count in calculating your average. Also, if a few of your professors know you, you can speak to them about maybe a grade boost. Don't count on it though.
It's not the end of the world. Just a minor setback that reminds you that you have to work hard to achieve your goal. Engineering is a difficult program, remember that.
Best of luck to you and don't give up hope just yet okay.