10:07 AM PT -- Bethenny just posted a photo of Dennis lying beside her dog, Cookie, with a farewell message to both, saying ... "Rest In Peace my sweet babies who gave me endless unconditional love." Cookie died late last year after suffering a major seizure.

Bethenny Frankel was extremely emotional Monday during a final goodbye to her boyfriend, who died Friday of an overdose.

Dennis Shields was found dead in his apartment in Trump Tower from an apparent oxycodone OD. Law enforcement sources told us Dennis took an unknown quantity of oxy Thursday night which he had prescribed to him. He woke up Friday feeling ill and asked his housekeeper to go to the pharmacy and buy Narcan -- which counters the effects of opioids. When the housekeeper returned home, Dennis was beyond help.