Ex girlfriend been best friends with my partner

My boyfriend and I live together its been 15 months im 57 he is 59 I was married 33 years he has been married once but divorced many years ago but was living with his now x girlfriend for 17 years Anyway they split and he met me but he and the x girlfriend are best friends and he has lied to me and taken her out to help her get things ect also they have drinks very often but he said its not in private but with other friends around I also caught him visiting her place when he told me he is with his mates there isnt one day that goes by without seeing her or talking to her im finding this a very huge stain on our relationship vut he wants her to be my friend and have her over to our place for bbq or drinks am I wrong I tried this but its not working for me he said I must give him the alternative

Given your mature ages and the fact that you yourself were married for 33 years should give you your answer here. Plenty of people are friends with the ex, but your if BF doesn't acknowledge your opinion about it all then you're not his priority.