In a relationship with man but curious

So like a lot of others on here I too started to get curious with women from watching lesbian porn. But I have a problem..I’m fucking jealous af. So I have often fantasized about a threesome with my bf but I feel like I would never get over the fact that there is another woman yet I see no problem with me doing it! I know I’m in the wrong I just don’t know how to overcome the jealousy. The jealousy is definitely caused by me being insecure about my body..so how can I help myself