The 'Kiss from a Rose' singer slammed his estranged spouse - with who he raises Leni, eight, Henry, six, Johan, five, and two-year-old Lou - for ''fornicating with the help'' and blamed her romance with Martin Kristen for their split in January after seven years of marriage.
Speaking after Heidi and Martin were pictured looking close in Sardinia, Italy, Seal told TMZ: ''That's what happens when two people separate, they move on and generally meet other people in their lives.
''I certainly don't expect Heidi to all of a sudden become a nun. But as always my main priority is the emotional well-being of my children, and to be quite honest, if there is going to be someone else there in their lives, I would much rather it was a familiar face.
''That's the only thing I would have preferred. Whilst I didn't expect anything better from him [the bodyguard], I would of thought that Heidi would have shown a little more class and at least waited until we separated first before deciding to fornicate with the help, as it were. I guess you all now have The Answer you have been looking for for the last seven months.''
However, despite Seal's claims, Heidi is said to have insisted to friends that her relationship with Martin - who has worked with her for four years - was ''strictly professional'' during her marriage.
One pal admitted the supermodel has got ''very close'' to her bodyguard since separating from the singer - whose hard partying was rumoured to have contributed to the marriage breakdown - but their relationship is currently ''undefined''.
The pal added: ''It's sad but not surprising that he would resort to making excuses for their divorce when the real reason is looking him in the mirror.''