How can I save my relationship

I need some advice: The problem in my relationship is a result of my actions. We have been together 7 years - there is 12 year age gap between us I was 17 and him 29 when we met - Trust has always been an issue - I made silly mistakes of talkin to another man early on and this man told my partner things happened when it didnt. Ive never felt secure with him and i always spoke to other bloke but it was simply it case they made me feel good about myself which i wasnt getting from him because he didnt trust me bit of a catch 22 - i know it was my fault the way he was but i didnt know how to deal with it all and i just seem to automiatcally grasp any attention ( im someone who hates to think because dnt like me or talk about me and what people may think of me). After 2 years we split up and were apart for a few months - He saw someone else - i didnt but he doesnt believe that - After we started seein each other again we had an argument about a month in and i went out and got very drunk and stupidly had a one night stand - A few months later i discovere di was preganant when i worked the dates i was sure there no chance a result of the one night stand - I do know anything about this one night stand not even a first name and the night is a blur. We split up during my pregnancy as he said he would kill me if i kept it - Deep down i knew that comment meant nothing but it stuck so i hid that i was keep the baby - When my son wa 3 weeks old he asked me if i had an a baby if he was his and i said i had and he was - We slowly got back together and he is the most fantastic father - but the trust issues carried on and i didnt help by seekin attention else where(ive never ever cheated except that one night stand but he had told me we were over during the argument - it was emotional/verbal attention) About 4 months ago we finally hit a point where it was make or break i finally opened up to him about how i was feeling and why i spoke to other blokes and i explained how i was struggling with my son - i went to see a dr and they diagnosed depression - i didnt want to go on tablets but i did see a cousellor for one session - we didnt discuss relationship just how i was coping with my son. My partner has always questionned parternity but it was only 2 months ago that i admitted to the one night stand - we did a dna test and i was very shocked to learn he is not biologically my son's father. We are now in a position that one min he wants to try and wants to be there for my son still as a father and the next he doesnt - he says he doesnt trust me and never will but that he loves me to bits - I understand that he must be hurting so much because my son is now 4 and we both belived he was his even though he had doubts - and i understand it will take time but i dont know what i should do because he is telling me that his life is in tatters and needs to save it before its to late ( i think he means because he 35 now) he says he will never trust me again - but its only a few hours ago he was saying he never wants to lose me. I want to prove to him that i love him and that i have never cheated and that i never will and that all i want is our family - anyway got any suggesestions? Ive suggest relationship counselling but he wont and i know it will take tme but i feel he isnt givin it even when he says he loves me and doesnt want to lose me? Im wrong feeling like that - I dont have anyone to talk to because no else knows yet and im scared to tell people because of what his family will say

We all make mistakes tell him how you feel and that your gonna live for your son and do whats best for him! Tell him let's work it out and leave the past behind or ill put you in my past I know you love him but time will tell and fix things so it's better to not gt hurt on purpose by him