Ok,I read a few of your posts.
There was no OM,so to speak.
Get tested for stds anyway..because you have broken all trust,I promise you he is wondering if you met men in person. Tell him the tests are to reassure him. The polygraph will confirm.
Also..you're scared of losing him. What you need to understand is he lost you. He feels that intense pain. You shared yourself with others,and he lost you. You will need to put in the work to make sure he knows you aren't going anywhere. So asking if it's selfish to stay will make him think you may not want to.
You have a lot of work to do. Don't expect him to do anything, for at least a few months, to repair the relationship. You need to show him,with actions,that you are all in. You have to do the heavy lifting. His job is to take care of himself, and watch your actions.
Understand, love bombing and lots of sex are not the work you need to be doing. I mean, yes, you need to be loving with him. But none of that makes you safe.
I tend to be very harsh with new WS,until they pull their head out of their ass. But you? I believe you have been in a lot of pain,for a long time. I think you sabatoged this relationship on purpose, because you felt you deserved nothing good in life. If you can bring up your self esteem, I believe you will be ok.
You did a shitty thing. But you can do the right things now. You also deserve happiness.