I'm not sure if I miscarried, and if I did, I need advise!

I was about 4 days late getting my period. But I didn't really think anything of it. The first day it was heavy for a few hours, then it would stop, and so on. The second day it was like black and had tons of blood clots. And the third day that night, I was passing like grey tissue about the size of a pea or kidney bean. Immediately after, I was cramping so bad, had a migraine, and lower back aches. I was in a ton of pain. The next morning I passed two kinda large red things. One I couldn't see because it was hiding in the hole of the toilet and the other I was able to partially see, but i couldn't get it out to look closely. And I started having severe cramps again. This time worse. My problem is, we were t planning to have a baby, so I had no idea I was even pregnant. So not only am I super upset, but I'm afraid to tell my boyfriend. We've been together 4 years, but I'm afraid he will get super upset and mad. But I'll feel guilty to not tell him. What should I do? And not to mention, but I feel like this is all my fault why I miscarried and I'm super upset. Someone please just help):