I think in an earlier post you were asking if it were possible to be divorced without being aware of it and it was decided that if your spouse had details of your current address you should have served a copy of the petition and notice of proceedings.
As you know you can get divorced after 5 years of being apart even if one party does not agree on the basis of your marriage being irretrievably broken down, if there are no children or property and your affairs are not complicated you can probably do this as a DIY divorce.
You mention the illegal wife, this marriage was void, it is quite possible that the woman with whom he now lives is unaware that she is not married, you are the legal wife, I doubt the pension paid to your husband’s current partner was paid as a result of a court order it is more likely to be your husbands choice, the court has very wide power and you should make sure of your financial position at court where you as the petitioner can obtain a decree Nici (meaning unless) and some 6 weeks later you can apply for a decree absolute then you are no longer married.