advice???

jessica

so my boyfriend (well now ex) had been dating for not that long but we honestly connect and balance eachother out perfectly, i am completely comfortable around him and he is the same with me, and 98% of the time we mesh perfectly, but one night i threw a party and i told him he cannot stay the night because my parents would drive by in the morning (it was at my cousins while i was dog sitting) and i told my parents it was going to be a girls night, but they know his car and would freak out, so basically he walked in with a half gallon of vodka and i instantly got mad and didn’t even want to talk to him because he started taking shots as soon as he walked in, so after that i sat by my best guy friend ever all night (let’s say his name is joe) and joe sat with me all night keeping me calm so i didn’t freak out on my boyfriend (we’ll call him mark) and so mark eventually got pissed off because i said a couple other boys (the ones who’s cars my parents wouldn’t recognize) could stay the night if they wanted and he was also pissed because i wasn’t giving him attention, mark then decides to just start chugging the half gallon and got himself blackout drunk and would not give me the alcohol and so i took his keys and had someone hide them (because i was so pissed i almost wanted to tell him to drive home drunk which i knew would be bad) and i went up to bed and put on a movie for myself. a couple minutes later joe, 2 of my other best guy friends (basically like brothers to me) came in with my friend (we will call her allison) and came to ask me if i’m okay. they then tell me mark is telling them that i’m all over other guys and won’t kiss him or anything infront of other people because i’m embarrassed of him and stuff (which i wasn’t until he got belligerently drunk and started acting like an idoit) so the next day mark goes home and decides to drink more (he has had a lot of drug and alcohol issues in the past and they have caused a lot of mental health problems for him) and i was mad that he decided to drink more and he began to text me saying how upset he was and all this stuff and i was pissed because he was drunk again in the morning so i was being very short with him and then the next day i explained everything that he did at the party and he realized how stupid he was, well 3 weeks later i found out that the day he was drunk at home he was texting his ex girlfriend for advice because he said he was suicidal and was crying all day even though he did not tell me any of these things and then his ex was worried he was going to kill himself (they have stayed friends since they broke up a couple years back and always go to eachother about this stuff) and they ended up kissing. then the next day he went to her house and watched movies with her all night and were making out and fell asleep together. a few weeks after it happened i found out from a text message that they had hungout together and that he didn’t tell me about it and the text message said something about him cheating on me and i asked him about it for days what happened and he said that she just layed with him and she kissed him on the cheek and i grilled him about it for days because i didnt believe him at all and eventually ended up asking his ex what happened and she told me the real story. i then talked to mark and he told me that he honestly got such bad anxiety and got into such a depression (he has major depressive disorder, bad anxiety, ptsd, hppt, and seratonin sydrome) and he told me that he was so upset and because i was ignoring me that he thought i was going to breakup with him or cheat on him and that the girl had been telling him that i’m a slut and get around and try to hookup with all of my guy friends (the ex has ruined multiple relationships before) and that she made him believe all his irrational thoughts and he was planning to breakup with me next time he saw me because she convinced him that i was trying to hookup with all the guys (she is also friends with all my guy friends) so mark believed it and that’s how they ended up kissing, and then the next day he went to her house after work because she was “worried about him being alone all night” and that’s when they made out and fell asleep together. i am a very forgiving person and i have cheated on someone in a drunken fit of anger before too and it was one of the biggest mistakes i’ve ever made and i have always wished i would have gotten a second chance. mark has also never made any type of mistake like this and genuinely hates hurting people, he has been extremely depressed and suicidal since it happened and feels awful for it because he now realizes how much i actually love him, and even though he fucked up i couldn’t completely cut him off because i didn’t want to see him kill him self over something like this and so i kept talking to him (not exactly being nice to him but making sure he knows that i’m here for him and i don’t want to see him hurt himself) and eventually i realized i kind of want to give him a second chance because he knows how bad he fucked up and i genuinely believe he won’t do it again so i told him there is a possibility of us getting back together in the future if he keeps trying. so we have been talking and aren’t technically together and the other night i ended up having sex with one of his friends so now it isn’t exactly “even” but we both have done fucked up things to eachother and both regret it and have realized we only want eachother, but not being able to trust him is already putting a strain on the relationship and we aren’t even back together yet. is trust something that can be rebuilt or are we both always gong to have those times in the back of our heads and keep bringing it up in every fight? or will we move on from it? is it worth it for me to give him a second chance or should we just keep it at friends? please help i honest to god love this kid as a friend, boyfriend, and just as a person in general but it doesn’t seem like it is getting any easier to move on from (even though it’s only been a week) what should i do????