I just almost got into a car accident. I'm freaking out. What I do now?

I'm 17. I've been driving since March of this year. I drive myself to and from school everyday. I almost got into a car accident that would've either killed me or someone else. And it's entirely my fault.

To get to my house from my school you have to get onto the highway. To turn right to get on

I'm 17. I've been driving since March of this year. I drive myself to and from school everyday. I almost got into a car accident that would've either killed me or someone else. And it's entirely my fault.

To get to my house from my school you have to get onto the highway. To turn right to get on it, you have a yield. I take this route everyday. And I messed up. When I pulled up an 18 wheeler was making a left hand turn which blocked traffic coming in. I assumed that I could've gone because there was no traffic.I barely yeilded. When I pulled out into the highway, a huge SUV was all of a sudden on my tail and I had to swerve out of the lane into an area that was outside of the lane. If I wouldn't have moved out of the way, the SUV would've hit me going 70 mph.

I feel like an idiot. I'm freaking out because if I would've waited one second longer he would've hit me at 70. This is the only major driving mistake I've made. I don't know why I didn't just yield.

Other answer:

macintosh46:
Change your underwear and then learn from the experience.
One lesson behind the wheel to take to heart is never to assume anything. Look at every other car and driver on the road as a threat to be watched and avoided. Same with neighborhoods where there are little kids around who can be very unpredictable. All threats.
Don't count on your cars performance to keep you safe (eg speeding up fast because you turned into a too small opening) Take it easy behind the wheel
Collin:
People are human – and fallible. You'll honestly feel better with time, but take this as a lucky opportunity to avoid making a mistake like that again. You're extremely young, and driving is still new to you in a lot of ways. It takes a lot of hours and possible near misses behind the wheel to make you a veteran driver. Cut yourself some slack, but don't forget the lesson you've learned.
Ron:
Almost only counts in horse shoes and hand grenades……..and pulling out. So freak out a little and get on with life
Bob:
learn from it