Precum on hand

There is no chance of you being prego, the only chance you could be prego is if you had penis and vagina intercourse without protection and he came inside you then that would be a high chance of becoming pregnant. you can breath and be rest assured that your period is right around the corner. And realistically it is not common.

It is theoretically not completely impossible. Probably around the same area of you getting pregnant by sitting down in a hotel room while fully clothed. The thing is pre-ejaculate contains a very very tiny amount of sperm, It is almost entirely the sperm from the last ejaculation, so if it's alive it's very near the end of it's life, weak, virtually impossible to penetrate the egg in the best circumstances. Sperm doesn't travel very far outside of fluid and doesn't live long in UV light or when not insulated in fluid. Sperm also doesn't usually make it very far in fluid, it relies on being released very close to the cervix to be able to find the guidance to your ovum and survive the swim with enough strength to be able to impregnate the egg without dying in it's short 20-some hour lifespan. Million-to-one odds pretty amazingly generous odds for this.

It's not good that this is stressing you out so much. This is an unhealthy paranoia and the stress is more likely the culprit of your cycle going wild than unstopable uber sperm. You may want to take some head-time and evaluate why the risk of pregnancy with this person freaks you out so badly. Maybe a bad life decision is being ignored here or perhaps you have an issue you need to resolve before having sex with them again.