HELP - Should I get an emergency contraceptive?

Yesterday while my bf and I were having sex, as he was going in we heard a snap. We looked at each other like "wtf" and checked the condom and it was broken, he pulled out basically raw.

The condom was completely off at the top and just wrapped around the base of his penis.

Before the snap we had been going along for about 20 mins, and he didn't ejaculate at all.

After it broke/we heard the snap, we put on a new one. My period ended 6 days ago from today, so I won't get it soon anyways. I'm still pretty worried.

Should I buy a plan b??? Please help!