What Are The Chances Of Pregnancy After Having Non-penetrative Sex?

me and my boyfriend were making out a week back...he was wearing his underwear n i wasnt wearin nethn.....he touched his penis wid my vagina for sm 30 secs through his underwear bt he dint ejaculate...later on he took it off n ejaculated on my abdomen.....wat r my chances of gtin pregnant?...m v scared...plz help..