I see that you are here in the USA. here relationships whether they are acquaintances, friends, close friends, friends with benefits, committed to each other or exes of any kind whats reasonable and not reasonable is a personal choice depending upon those in the relationship....

in other words it is up to your husband and his ex wife to say what is reasonable and unreasonable in their after break up relationship.

the same goes for the ex's side of the family... it is up to your husband and his ex inlaws and so forth to decide for their self what is reasonable and unreasonable for their relationships.

think of it this way... your husband can not say who you can and cant be friends with and what kinds of contact with your friends is reasonable or unreasonable. it is you that gets to decide that.

my suggestion is that if this continues to concern and worry you, talk with your husband, explain why you are feeling uncomfortable and work out with him what your marital expectations are in regards to ....... both.......... of your contacts with ex's. I say both because its normal for husbands to have ex's and its normal for wives to have ex's in their lives whether those ex's are loved ones or doctors, or co workers and so forh. this is a marital issue that needs to be worked out between you and your husband on marital expectations where contact with various ex's are concerned.

how my wife and I worked out this situation was that we both sat down and talked and we both feel each other has equal rights to have friends and choose their own friends and that includes our past relationships of any kind. I have my ex loves and she has her ex loves and sometimes we do have contact with our ex's. and we dont place any limits on each others friendships and contacts with ex's. on both sides my wife and I consider the ex's family. for us we didnt stop loving those people in the ex family just because we fell out of love with the ex. for us they are still family, and if any of them need us for any reason we try our best to be there for them. we have all gone through natural disasters, deaths and illnesses together. it was actually an ex side of the family that stepped up with my wife and I lost our home to a hurricane, it was an ex that stepped up when my daughter needed after surgery care and both my wife and I had to work, and my wife and I were there when an ex's wife died of covid this past year.

I can understand that you feel upset and concerned about your husband but what goes on between your husband and his ex and that side of the family it up to them to decide what it reasonable and unreasonable. thats life in america. freedom to choose and live ones own life including friendships with ex's and ex's family the way we choose to.

talk with your husband.