LINDSAY LOHAN explodes in jealous rage over SAMANTHA RONSON?

LINDSAY LOHAN exploded in jealous rage when a mutual pal revealed that ex girlfriend SAMANTHA RONSON just proposed marriage to new love ERIN FOSTER. Lohan reportedly phoned, texted, e-mailed and sent messages through friends, begging Sam to call her back ASAP!

"She was seething when she got no response," said an insider, "but that shouldn't surprise her -Sam's still very upset because Lindsay offered NO compassion or sympathy after her shock DUI arrest."

Said the source: "Lindsay's beside herself! She knew Sam was dating Erin, but had no idea it was serious enough to trigger a marriage proposal.

"She told me: 'I can't believe that after everything we've been through together, I had to hear about this through the grapevine!'

"Then she hissed: 'I hope those two #&%$ will be very happy together!' "