Can't get over boyfriend ual past?

i dated him for a year and 4 months, he has an ex gf, and i have ex too. but i nvr do anything with my ex, just kiss, but he and his ex get naked together, and he even fingered her before. these thoughts are making me crazy, and jealous and it's torturing me. i love him so much but i want to get over this or else it will ruin my relationship when i always talk about this to him. HELP.