My boyfriend ejaculated on my tummy, but he suddenly wiped off the sperms. It was my third day of my menstrual period. After wiping the sperms I went to washroom and wash my vagina and tummy with same hand. Could I get pregnant?
Any time you get involved in acts of sex, there is a chance that pregnancy can occur. Since I don't know exactly what was done, I can't tell you want the odds are. For example, you mentioned that he ejaculated outside of your vagina, but that doesn't tell me whether he had his penis in your vagina before that point. A boy's penis drips pre-ejaculate fluid when he is sexually excited and that fluid can contain sperm.
You can only get pregnant 14 days before your next menstrual period, but a boy's sperm can survive up to six days inside of you. So any sexual act between 20 and 14 days before your next period can lead to pregnancy.
But pregnancy is just one problem. He wasn't using a condom, so the chances of passing a sexually transmitted disease is quite high.
However, the most severe problem is that you both were violating the laws of God. "Marriage is to be held in honor among all, and the marriage bed is to be undefiled; for fornicators and adulterers God will judge" (Hebrews 13:4). You cannot reach heaven while being involved in sin.