Dark Brotherhood vs Thieves Guild

Ok. I just got kidnapped by TDB. Woke up in an abandanded shack. Did the duty of killing someone. Got the invitation to join. Although, when I got back to Riften after finding Esbern, it seemed like there was a hit squad after me. I was obliterated. I reloaded took a different route to the Theives Guild, and we got ambushed. I finally got him to Riverwood to meet up with Delphine after some vicious fights. Is this because I killed Grelod the Kind? Or, is this is what I have to look forward to now:) Anyone else went through this?