Just leave it, find someone who has no sexual history and start again
This is the most shittiest advice ever! I can’t believe someone actually said this 
I don’t really see the problem with him sleeping with others
DP and I were together for years when we broke up for 9 months. 6 weeks after he finished with me I was sleeping with someone else. A few months later I even formed a relationship with another man! (Which didn’t work out as I still loved DP)
I look back now, and even knew at the time, that the reason why I was sleeping with someone so quick was to try and mask the hurt I was feeling. I had no interest in him and I thought it would be something ‘fun’ to help me get over the break up. The guy was fully aware of what it all was
The second guy I met later on I did actually have feelings for. But I still loved my ex and knew it wasn’t right. DP and I ended up back together and I’ve never been happier.
I wasn’t wrong to sleep with either of them. Just like your partner wasn’t wrong to sleep with them two women. Me sleeping with those two men doesn’t take away the love I felt for DP. It certainly doesn’t ‘tarnish’ anything 
All I’m saying is - you two weren’t together. Just because YOU see sex as something more personal it doesn’t mean he has to aswell. He’s done nothing wrong.
The way you see things such as you being the only woman in his house and how you were his first and now that’s all tarnished - he isn’t a possession! He’s not damaged goods just because he’s now had another woman in his house. He’s not your “territory”
I think what bothers me is I have a face to the name of one and she’s skinnier, younger etc
I’m sure if she’d been the same age/older and fatter you probably wouldn’t be feeling so jealous which is why personally I think you’re being so shallow and OTT about all this
You’re jealous because he slept with two people when you weren’t together - you don’t like the fact he’s had another woman in his house (HIS house, not yours). You’re insecure because you know one woman was younger and slimmer - your problem feeling inferior to her.
I think you need to massively work on your self esteem. All your ‘reasons’ for feeling so upset about this are shallow and superficial. If this is how you normally are, I’d find it suffocating aswell and would probably need space to breathe. You see him as a possession you own and now it’s all “tarnished”.
If a man came on here and said his girlfriend was tarnished for sleeping with another man on a break he’d be flamed.