no judgement please

I've been with my SO for a little over two years now (we've broken up a few times- twice for a month at a time). And when we broke up the first time i slept with my high school f**k buddy. And once me and my SO got back together my FB didn't stop texting me begging for me to stay with him instead. I didn't know what to do. My SO was great in bed but not great to my relationship wise. So on the downlow I kept seeing my FB because he just gave me the attention i wanted and needed at the time. When me and my SO started to get a better relationship (about 6 months while seeing my FB) i cut off ties with my FB completely. About seven months later we broke up again, and again I started seeing my FB again because i thought me and my SO were through for real this time. After a month with my FB, my SO came back begging to be together again. And at first I wasn't all for it but then I decided i still loved him so i gave him another chance to be the good boyfriend i know he could be. For about a month i kept in contact with my FB but never hung out with him. One night i came back from the bar with my friends (drunk) and i told them my ride home was going to pick me up at walmart. So my FB came and got me because my SO was not answering. We were driving home (not planning to do anything) but i guess my drunk self got the better of me and I started touching him. He pulled over and said that it wasn't right because i was so drunk but I wasn't that drunk so I assured him i gave my consent to whatever we did. And he even made me do some of the basic drunk test things. I was sober enough to know what i was doing. We ended up having sex and then he took me home. He ended up getting a girlfriend and we decided to take a break on talking because neither of us wanted to ruin what we had. We haven't spoken since May of this year. I've never told my SO about anything except for the first time we broke up and when i first had sex with my FB. But anything after that has been a complete secret. I know I'm a terrible person but how do i make myself feel less guilty about everything without ruining my amazing relationship now? Please no judgement. I know what i did was terrible.