My husband and I have been happily married for 40 years, he has always loved the company of women around him. But, a friend of ours (was of mine) always caused an argument when we three went out for dinner, etc. She would tell lies, and of course, I always reacted, so then my husband, believing her lies, accused me of always causing the argument. Since then, she attacked me, but told my husband that I attacked her, he believed her.

I have spoken with him many times, but he says, that he will take her out without me. I know he loves me more than anything, as I do him, but she is now in her element, knowing that I will not be invited out with them or go back to her place for a coffee, or whatever. She phones him, & he to her, they sent emails to each other, when I sent something personal to him, he sends it to her.

I really don't know what to do, he doesn't see the hurt this is causing me. He said, you two have a problem, fix it. This has been going on for over 2 years now, and I am at my wits end. PS. She flirts with him all the time, but, I honestly believe that they are not having sex.

Have you tried to calmly talk to him about it, while she's not there?
Explain to him that while you trust him you don't always trust her and that it makes you very upset to see him go on a date with another woman alone. If he's sensible and really understands how upset this makes you, he may decide not to go. Also explain to him that if he's going to go that you would really like to be there as well to spend time with him, also point out that you will be on your best behavior and will do your best not to instigate any fighting (which I would advise doing if you want to keep your friend and your husband).
It seems as though your husband doesn't fully trust you if he's willing to take the word of another woman's over yours. Perhaps you should point this out to him and ask him why he won't believe you. Also asking him why he wants to see her so bad is also advised.

If you do go out to eat with her maybe you should invite someone else along that will help break up her lying and give her another point of focus besides you and your husband.

Also a part from talking to your husband you should also have a word with your friend. If she really is your friend she will listen to what you have to say. Be nice though! You don't want to give her another reason to fight with you. Just explain that it makes you feel uncomfortable and that you want to remain friends (even if you don't... but for the sake of your husband) you might also throw and apology in there somewhere to make her feel like she's won.

I don't really know the whole story so I can only base my judgement and advice off what you've said. But, if your husband really cares for you he will listen to you. Forty years is a long time, I'm sure that he just thinks he's being friendly and doesn't realize that he's hurting you (men are sometimes oblivious like that).

For a husband to choose another female over his wife, is unnaceptable, and the three of you need to clear the air. Why do you think he takes your word over hers? Why do you allow it?