Boyfriends Son/Ex/Drama?

My boyfriend of nearly 3 years was in a relationship with a woman called S for a year before we got together and there was a 6 month gap between splitting with her and getting with me. Before her, he was with a woman A who he got with when she was 3 months pregnant with another mans child. They were together for about 4 years and he raised R as his own even when they split up he looked after him every weekend until a week before his 5th birthday when A stopped him seeing R. Now R is 8 and last weekend friends of ours went to a wedding (we didn't go because I knew A and R would be there and I knew it would hurt my boyfriend to see him). So our friends spoke to them and found out that A stopped my boyfriend seeing R because S had been messaging her slagging her off and causing trouble and A thought my boyfriend knew about this. Our friends cleared this up so A said if my boyfriend wanted to he could start seeing R again because it wasn't his fault he was stopped contact. My boyfriend has gone in to a self destructing downward spiral finding all this out and hes so lost at the minute I don't know how to help him. I tried explaining that if he started contact again (R still knows him as dad and remembers him) he would have to be there for atleast the next 10 years as it would mess with the boys head. He said he would want me to be involved if he started seeing him again but i'm 19 and he was born when I was 11 so I think it's a bit weird plus I wouldn't want it to be uncomfortable for anyone. My boyfriend is the softest, kindest person I know and I don't want him to get hurt. Plus i'm unsure weather A is just trying to get her claws back in. His name is on the birth certificate and yes I have explained to him that this is illegal. And the child took his middle and last name although these were removed when contact stopped. What should he do? Or what should/can I do?