SURVIVING INFEDELITY-JEALOUS-DEPRESSED

Here is my story. My husband and I have been together for 16yrs(he was 16, I was 17)...we were high school sweethearts and what I believe to be soulmates. He lost his virginity to me...I had sex with a few people before I got with him. I found out about 8months ago that he was having an affair with a 23yr old. It lasted for about a month 1/2. They started the relationship on FB and met up after a few weeks. They had sex 3-6 times(depending on who's story to believe) hers or his. We got into a huge argument and he said he was leaving and staying with his parents that night...16 hours later I begged him to come home and he came clean about everything. He said he stayed at her house and told me about them. He said he planned on leaving me and that argument was the straw that broke the camels back. He also admitted that he had a 1 night stand 2 years earlier at a bonfire with someone unnamed. Said he has been unhappy and he was "curious" since he had only ever been with me. I begged him to stay bc I didn't want to lose him. After a few hours he decided to stay and messaged the other girl and told her it was over. We have been working on our marriage, went to counseling for a few months...everything was getting better. We were having sooo much sex...it was like a wake up call and it sparked a sense of like a new relationship. The feeling was amazing. Now 8 mo later the feelings of extreme jealousy, depression and just sadness are hitting me sooooo hard!! I can't stop thinking about the other women and him having sex. Was she better than me? Skinnier than me? Tighter than me(she's 23 w/o kids). I can't get these thoughts out of my mind!! He told me that he had not had sexual intercourse with anyone since the bonfire girl and this girl in the past 2 yrs. I find myself snooping through his phone and fb to see if I can find any clues of other people. It's like an obsession! He had soooo many girls on his fb profile that he was actively looking to find someone else(he messaged girl on messenger) that's how they "met". I really believe there was others but no proof....I really try to believe him when he tells me I am soo much better in bed, she was a dead starfish and that it was just something "new" that's why they had sex a few times. He told me this like 6months ago. That I'm 100% better and in a way he was just looking for the "old Christina". He said there is nothing to be jealous of that he blocked the affair out of mind along time ago and doesn't even think about it. I hate the fact that I keep bringing it up and making him think about it...but it's like I need that re-assurance that I'm the best. I keep comparing every little thing to her and it's driving me insane! I was also thinking about asking him for a name of the one night stand from 2 yrs ago....but I feel like then it will just make me obsessed with her too. BTW he didn't use protection and she said she was trying to get pregnant. He said that he thought me and him were over and that he didn't think he'd come back. So he was just going with the flow.....this depresses me soooo much. I was the only one he had sex with and now I have to worry about comparisons and he knows what other girls "feel" like. That disgusts me soo much. I need advise to get past all this....should I stop bringing it up? Should I ask more details?? That will prob just hurt me more though. Please help!!!!