I feel like im in a really bizarre situation and have nowhere else to turn to for help.

So for context, my partner (34 m) and I (26f) are poly (sex and dates only and preferably together) and we've successfully dated people together for the last couple of years. We've had some really lovely and positive times with some gorgeous people and I love this aspect of our relationship.

However, my partner was talking to this person a year or so ago who he thought could be a good friend and potential sexual partner for us. I wasn't really keen as they were early 20s and I wasn't really comfortable including anyone in our poly stuff who wasn't experienced/mature. For example, all the people we've been with previously have been around the 29-32 mark. Also I found this indivual a bit irritating as they seemed a bit chronically online and trollish. Seemed funny at first but it just ended up very grating.

However, I started feeling a bit sorry for them as they had some troubles with mental illness that i also had experienced and wanted to help them. I decided I could be friends with them and this indiviual and my partner could explore sexually if they wanted to. Against my better judgement I flirted a bit too because, like I said, my partner and I prefer these things together and ended up getting invested in the situation.

Anyway it transpired that this person was posting screenshots of private messages they had with my partner, out of context on instagram and to other people which made him look like he was kinda begging for this person whilst being in a relationship (despite the fact we are very openly poly) and was I guess mocking him? And insinuating he was cheating. And this was without his knowledge. This led to people saying really horrible and untrue things about my partner. We said how we didn't find this appropriate at all and found it quite rude and took some time out talking from this person

We later found out that they were also talking about us in a derogatory way behind our back to a guy friend and they were insulting my partner's character, our relationship, my looks etc. When called out the person acted as if we were at fault for blowing everything out of proportion, rather than acknowledging that they had betrayed our trust and hurt our feelings.

We blocked this person but they tried various ways to get back in contact with us. It got to the point where I considered reporting them for harassment as they were unrelenting and even gave our numbers to random people.

During this period, my partner was hacked and his first thought was that it was said person who we had blocked, as an attempt of revenge. Just to give an insight of this person's character...

This person brought a lot of drama to our life and I feel too old to deal with it, I love and value my peace and positivity and I didn't get any positive aura from this person.

Now a year on, my partner has been feeling like he needs more friends and was missing the fun conversations he had with this individual. Subsequently, he unblocked them and has started speaking to them again.

I'm personally furious because I feel this individual disrespected my partner, myself and our relationship in such a vile way. I feel like my partner should have my back but him speaking to this person again feels like he is saying its ok to trash him, me and the way we conduct our relationship.

If things became sexual again between them, I'd feel like a laughing stock because of the insults made against my appearance. However if I put a no sexual conduct boundary, I'd be accused of being jealous/insecure/controlling if not by my partner then by this person.

Also if that happened I don't think I could stay in the relationship, but my partner sees that as me giving ultimatums as I supposedly "know he is going to choose me" so he feels like I'm forcing his hand and being manipulative. But I just genuinely can't be in a situation where I feel disregarded, disrespected and unvalued?? I may be poly but I have feelings and I have boundaries yknow??

Anyway my partner is taking this quite poorly and feels like I'm being controlling and trying to stop him from having friends out of jealousy and am changing my stance on our poly relationship. He says people deserve second chances and he wants to forgive but I kinda believe in only having good people in your life who enrich every aspect of your life and who inspire you to be the best version of yourself.

Regardless, i dont feel jealous and I dont want or intend to be controlling. But our relationship is so precious to me and whether or not people agree or understand it doesn't matter to me, but I've never had anyone treat our relationship as such a joke before. I always say that the only opinions that matter are ours. But with him befriending this person again, it makes me feel like he thinks our relationship is a joke.

I also have struggled and overcome a lot of issues with self-image and it is really hurtful that he would unblock and get back in contact again with someone who has targeted insecurities that I've worked really hard to overcome.

I feel a bit betrayed honestly. But I also dont wanna be a controlling asshole. But I also think I deserve to be supported and for him to have my back.

We are usually so good at communicating but I don't see a way around this which ends with no resentment on either side.

He has had a past of being in toxic relationships/having toxic exes (can legitimately confirm, not being one of those ur ex gfs are all insane ppl) and I think he just finds the drama so addicting. We are passionate but rarely have any true conflict and we can get over issues in a health way but it feels like he is getting some sort of dopamine rush from all of this after suffering with some blows in recent months (didn't get the promotion he wanted/boiler breaking/family disputes). Anyway I just think he's pressing the self destruct button and it's driving me away.

Any thoughts or advice would be welcomed as I'm at a loss.