Am I wrong??

Okay so my husband and I have this friend, we’ll call him Sam. Well about a year after my husband and I started dating, Sam got a girlfriend, who we will call Jen. When Sam and Jen were dating, we didn’t really hang out much as couples, but we did occasionally do things. Jen seemed nice and like someone I could get along with. About a year into their relationship, Sam told me (we are close and I am protective of the guys in my life bc I know women can be vicious, too) that Jen cheated on him with a dead beat who does drugs, was in and out of jail, and has two kids he can’t support. He was sad and depressed for literally MONTHS. My husband and I were there for Sam and continued to tell him he deserved better. Sam even told me that Jen had experimented with heroin after they broke up. Then we found out that Jen had gotten pregnant by this guy she cheated on Sam with. Between cheating on him and shooting up with her dead beat boyfriend, I told Sam I do not like Jen, they way she treated him, or the fact that she is a PRESCHOOL TEACHER who thought doing heroin would be a good idea.

Fast forward to the last 5 months or so and Sam has been hanging out with a new girl, which happens to be my sister. They constantly talk/text and they are always doing things that couples do, but he says that they are just friends and is sending mixed signals to my sister. He told her he could see them together in the future, they have been traveling together recently, and he says things that “friends” do not say to “friends”. He says he doesn’t want a relationship right now, which is fine, but he keeps talking about getting back together with Jen and how they hook up sometimes, but usually she is really short with him, makes plans with him and bails, and is just really shady. For some reason, none of those things bother him. I want to be supportive of him, but I told him I WILL NOT hang out with him as long as he is with her because of how she treated him and continues to treat him. I’m also pissed that she did heroin because if I found out my child’s teacher was doing that in her free time, I would be LIVID. Anyways, Sam keeps asking me to hang out with Jen and give her a chance because “I don’t even know her” and “I’ve never even hung out with her”. I told him I don’t have any interest in being around someone that has done the things she’s done, nor do I want to see him hurt again. Also, when he and Jen were together, he would always tell me about how they were constantly fighting and arguing and he literally seemed miserable.

So I guess my question is, am I being irrational for not hanging out with Jen? Am I being a “shitty friend” (HIS WORDS) for not supporting a relationship between the two?