should hubby still be friends with a chick who i feel is after him??

whilst separated for nearly 5 months, i found out by accident that my friend of 11yrs and hubby were having a very detailed conversation that looked like they were planning on sleeping together. meanwhile, im pregnant with our 4th child and started to get really annoyed. I then found a picture of her breasts on his ph, and decided not to trust her anymore, so i broke off all contact without even telling her that i wanted space, she found out i had deleted her from my facebook account, and one evening my hubby wrote a comment about the NRL grand final saying DUMB GAME, she wrote to him poor baby lol.... Under that he had written, leave me alone to cry by myself HAHA.... under that i wrote directly to him not to her, its ok baby i will cry with you... Love u xxx.
She wrote back "Go F urself" then my name when i sent her a msg in private she made up excuses of being drunk when she sent the pic of her breasts, that day because of the stress i was under i ended up in hospital with my blood pressure up high, i hadnt had a chance to tell hubby bout my email to her.. a couple of days later she started causing trouble again and talking to him and calling me names. Hubby wouldnt listen to my side, until the next day i had to text him at work to get my point across, he then seemed better towards me and has been alot more loving towards me, but i still feel uneasy about their contact