I am sorry to read this.
Let's have a look at what happened ~ and I hope that you won't mind me asking some questions
You say that he is the love of your life and that he said that he felt the same way about you.
You are both in your early 30s, so you are close in age.
But are there any other major differences?
I take it that you are Scandinavian and he is English / British ~ has that difference in backgrounds caused any problems?
Have you had similar levels of education?
Do you have similar religious and political beliefs / opinions?
Do you have hobbies and interests in common?
You say that you moved from Scandinavia to the UK to be near your boyfriend.
How long have you known your boyfriend?
How long have you been together as a couple?
How and where did you meet?
When did you move to the UK?
Were you living together in the UK?
Had you lived together before?
You say that you were working on sorting things out between you.
What sort of problems did you have?
Were you able to make up afterwards?
Everything seemed fine, to you, but when you went to Scandinavia for medical treatment, he sent you a text ~ breaking up with you.
So, obviously, things did not seem as fine to him as they did to you.
You say that 'every aspect of us living together has been great', but, if that were the case, then he would not have ended the relationship. Something must have been going on in his head that you were not aware of.
Apparently, a woman has told him lies about you, but, if things were going as well as you thought, then he would not be listening to such gossip; he would be talking to you about it and trusting your responses.
There are two possibilities:
1. While you were gone, he realised that things seemed better without you, for some reason.
2. He really does believe what this other woman says ~ perhaps because he lacks confidence, or something.
What can you do?
I think that the best thing might be to write him a letter.
You could ...
~ Explain how you feel.
~ Tell him that you did not do the things he has been told about.
~ Ask him if that is the only reason that he broke up with you.
~ Assure him that you love him and that you do not want to break up.
~ Tell him that you are confused by his behaviour and that, if he is intent on breaking up, then you would like to know why.
~ Speak in your own words ~ from the heart.
I hope that you can sort this out, but it may just be that he feels that the relationship is over. If that happens to be the case then, sad as it is, it will be for the best, because you would not want to be in as relationship where things were not as they should be.
If that does happen, then you would need to spend time with people close to you; take care of yourself and allow yourself to grieve for this relationship.
You are still quite young. You have time to make this relationship work ~ or to move on to find a new love.