he thought about cheating

i want to start this by saying i have always thought of my fiance as being extremely loyal and devoted towards me. he deleted his entire following on social media, always calmed my worries or didn’t even get into situations where i would question him, and has been there for me since day one. he was cheated on by his last girlfriend and he told me everything to do with it and how it affected him. we’ve obviously have had plenty of talks over the time of our relationship about cheating and boundaries with other people and had come to the same thought process of hating cheaters. so the other night my fiance told me that he had thought about cheating on me sometime between february and march. he told me that the lack of sex we were having, which was basically nonexistent at the time, was really affecting him mentally and he had the thought of seeking someone out to get that intimacy. he has told me in the past and again recently that while different things like being verbally affectionate, doing acts of kindness, and cuddling do show him love, having sex is much more intimate to him and shows him how much i love him. he told me how he talked to his older coworker thats married with two kids if he ever thought about cheating on his wife which his coworker said yes in the beginning after their first kid but not anymore since he’s understood better how to communicate and show his love for his wife better. ive been trying to be understanding of his perspective. we were barely having any sex until recently, like going up to 2-3 months at a time with no sex or only once in that time. ive been constantly busy and exhausted with our baby (9 months) and just last month got him on a normal schedule sleeping through the night. i know i’ve neglected my relationship and my fiance in trying to focus on my baby. i know we’ve been distant and havent had much time to just spend with each other. i know what lead to him thinking i didnt care about him as much or didnt love him as much. but im REALLY struggling with how my entire perception of him has changed. i thought of him as completely faithful and loyal to me and would never look outside our relationship for some instant gratification. but its really starting to take a toll on me and ive told him about this, and he’s accepted that and told me i have every right to be upset/pissed/sad/disappointed in him. i just feel like utter shit about myself especially since ive had some body image issues since having my baby (which he also reassured me it had nothing to do with the way i look, it was all just him). if i could get some sort of advice from people it would really help. i dont need negative comments about how he “probably did cheat” or that i should dump him. i trust him and him even telling me on his own without me even prompting him to just goes to show that he’s still somewhat of the man i thought of him as.