<human>: Background history: I am struggling with severe insecurities due to past encounters with men as well as past with my boyfriend.  We've had a long, difficult history of hurting each other and not trusting one another (neither's fault) and so now both suffer with insecurities/trust issues, but my insecurities are far worse.

Basically, my boyfriend sometimes has intrusive thoughts of other women, either those he has had sexual encounters with previously or random women he knows/isn't attracted to. I hadn't asked about the thoughts in a while but the other day asked (straight after we'd had sex) if they'd gone away. He said no, I asked if they had just happened and he said yes. I also asked who and we both ended up very upset. I know it's a mental issue and he hates it as much as I do, but it's always on my mind when we have sex.  

Anyone been in a similar situation and know how to deal with it, as well as other general insecurities:
- thoughts of him being intimate with his past relationships
- worrying that he will leave me for them
- constantly wanting to question him on his past (we both already know pretty much everything and are overly honest, which I now regret)
- worrying that he is checking out other women

Give me a shortened version of the text
<bot>: How do you deal with severe insecurities and knowing that your partner has unwanted intrusive sexual thoughts about other women while you are intimate?