Thrown out of ex's house without being allowed to collect all my stuff, am I allowed to break in to get it back?

My relationship of 4 years has just ended. We lived together in a house belonging to her parents. I paid money direct to her + she passed it on to her dad,I had no formal arrangement or bills apart from my phone contract because she said she had been burned before and I didnt think we needed it. Everything was managed through my ex or her parents. I paid money to my ex for my part of bills, in fact I probably paid the most money about 80% of my income for everything.

I think my ex has some undiagnosed mental health / personality disorder but any time I tried to hint at her getting help she would go loony and say I was gaslighting her. And then she started being obsessed saying I was cheating on her because she found out I was speaking to MY ex GF's mum (relationship ended like 6 years ago on OK terms but me + her mum were really close and stayed i ntouch) and assumed I was seeing my ex behind her back even though we havent spoken in years.

We had an argument, she tried hitting me with a glass, and I grabbed her and pinned her to the wall and told her she would not do it again. Then she got her brother in law to come around and threaten me and basically gave me a rucksack to pack with my stuff and get out. I had to make arrangements last min as they were ready to chuck me on the street.

They also wouldnt let me take a lot of the stuff, saying it was stuff they bought and not mine INCLUDING a gaming PC her parents bought me as a supposed thank you for some major work I did for them last year.

This all feels wrong and unlawful eviction but I really dont feel like arguing that right now. The computer and the other stuff is more important because it has personal data on there I would like to keep access to and there are some of my other belongings she didnt give me a chance to take.

She made me give her back the keys but last year after another stupid argument I secretly had spares cut and hidden on the garden. if I let myself into the house with some friends to take my stuff back, is that burglary? Is there any chance either of us could be in trouble? I dont want things to be violnt but I feel like I have to get it while I can.

eng