Friends with friends girlfriend

I had a few male friends one caught feelings for me and the others just went away with him so never really spoke again. I know this is probably more than my own insecurity over anything but me and my husband have been dealing with infertility for 7 years. my husbands friend is a massive tool, he cheats continuously on his now pregnant girlfriend and smokes and snorts drugs all the time. I am basically feeling insecure, I have told him why. She calls and texts my husband all the time, asking where her boyfriend is and thrn guilt trips him into whether he is lying or not. She is a nice girl but I feel insecure because she is just to god damn nice, i am jealous of her because she is pregnant but even before she was pregnant we went out to have a few drinks together and she told me my husband slags me off to her when we have had arguments in the past. I have confronted him about it but he says its normal. she says if she wasnt with her boyfriend she would be with my husband bevause he is a good man. For people who commented coukd you tell me how to approach the situaion i dont really see this girl and i avoid her like the plague because of the whole pregnancy thing