Husband hanging out with old “friend”

OK, I need advice in a sense that it’s mature, respectful, and with honest opinions. My husband and I have been together for three years. He works at a bank and has been moved to different locations throughout those years. My husband is really good friends with his former boss who had feelings for him and who he had feelings for. He even wrote her a song and said he was depressed at the time because it didn’t work out even though he claims that they didn’t even kiss.

The girl was separated from her current husband, who did not agree with them seeing each other. Again, they were both separated but I guess the husband was jealous. He threatened my husband to the point that he had to buy a gun, and was always on the lookout for the girls husband to attack or whatever.

Eventually they stopped talking, and they both moved on. The past couple years she was still his boss but up until recently, he has been moved to a couple other branches due to staffing situations. My husband has applied for jobs, and has had projects to where he asks for her help constantly. He texts her, he still jokes around with her, sends her memes etc. I guess she’s even made the point that supposedly I hate her, which I’ve greeted her before when my husband asked me to bring him things to his branch…

Anyway, I do not hate her, I actually am appreciative that she takes the time as his former boss to help him with interview questions/things that are job-related. The thing is that when they’ve worked on work related things he’s gone for 3 to 4 hours. Again I understand that this is his friend but the fact that they had a romantic past, and the fact that there was trouble with the current husband, makes me upset. He went to mow her lawn once (she paid) I told him to not go. He stopped going.

I personally have set a distance with people who I used to talk to because of the same reason. We are still friends but we don’t hang out even if it’s work related, and all that.

Please give me your advice, I was trying not to be jealous, I’m also not trying to be overprotective because I do trust him.

There has been times however, that he is a little too flirtatious in my taste with other girls and I’ve confronted him about it. Nothing too serious but flirtatious indeed. I need an honest opinion I can see both sides of the spectrum, I don’t want to be possessive but I also think that because of the past there should be maybe more respect and better boundaries. He claims to have no feelings for her.

Please tell me I’m being overdramatic.

Thank you