Despite raising her child, ex proceeds to make my life hell!

I have been ordered to pay csa which I have no problem doing, but I feel slightly hard done by as I raised my ex partners son for 14 years and I didn’t once ask for any money back and now my ex partner is trying to make my life hell with csa, she cancels then she proceeds, this has been the process she has put on me. I’m concerned as I don’t think the money I’m giving her is going towards my son, Last Christmas she spent a mere £40 on my son and I spent around £400 not including the csa payment, I think this is so unfair, he stayed with me over the Christmas and the mother isn’t giving him the money I pay for csa. I would like to know what can be done about this as my ex is just trying to make life difficult for me because of her troubled upbringing.

I am not against supporting my child but when the money isn’t going towards my son then surely something has to be done.

Barring in mind I raised and contributed to her eldest son who isn’t my child. I just can’t believe someone could be so heartless even though I raised someone else’s kid and I didn’t have to. My ex partner has clearly stated to me that she is going to make my life hell and this is the result of it, I’m not sure of her mental state and I know she has been drinking a lot lately and she was even in hospital for related illnesses. I have been off work this week sick with flu so I was unable to go to the bank to transfer the csa money which I explained to her on Monday. I said I woyuld pay Friday the latest and now she is sending me threatening text messages saying she will report me to the csa! is this fair after I already explained the reason?? I can’t put up with this behaviour no more and she is really stressing me out. I cant believe people can be so cold especially when I raised her son for all these years. It’s just so unfair, I would like to know my rights as this can not be right surely.

I cant even contact my son because the mother turns his phone off and I cant ever get through to my own son, the only time I hear from her is when she wants money.