'16 and Pregnant' Star Whitney Purvis Speaks About Son's Death

Whitney Purvis is speaking about the unbearable heartbreak of losing her teen son Weston -- saying she’s struggling to even process the pain, let alone figure out how to keep going.

The "16 and Pregnant" star says she can’t escape the grief -- when she’s not crying over the loss of her 16-year-old son earlier this week, she’s just lying there, staring at the ceiling, trying to block out the pain that won’t go away.

Whitney tells PEOPLE she found out in the worst way -- she didn’t answer a call from Weston’s dad ’cause they were in the middle of a disagreement, but when he hit her with a "911" text, she knew something was really wrong. The second she heard the news, she screamed her lungs out in the car.

And it's been rough ever since -- Whitney, who was pregnant with Weston during the first season of '16&P' in '09, says she never imagined this would be her reality, and has never cried this hard in her life.

Now, she can't quite picture what her future looks like without him -- but right now, she's just grieving alone so she can process it all.

As you know ... Weston was found unresponsive in bed around 7 AM Monday, according to his stepmom Amy Gosa, who shared the heartbreaking news on Facebook.