Okay some info about me.

I'm 21 and suffer from depression and anxiety.

I also have cystic fibrosis.

My gf (20) female fortunately doesn't suffer from mental health issues so she finds it hard to understand how Im feeling.

Me and my gf have been seeing each other for 6 months now and she is my everything!

From the start of our relationship she was very open with me about how she had to go on placement to the isle of man (we live on UK mainland) for two months, which I was fine with.

However during this time, she started going out clubbing on her own over there and on one of these times she went missing for 12 hours and then messaged me the day after saying she had stayed at a guys house but in separate beds. I was not happy with this and it reopened previously healed wounds as I have been cheated on in the past. It's damaged my trust for her but she has more trust in other people than I do. 

When she was still over there, she received an email about a study abroad scheme where she can go away for two weeks (17 days) to France. Before this she said that the time away from me has made it clear that she doesn't want to be away from me anymore, but as soon as an opportunity comes up she jumps straight in!

The plan with placement from the start, was for me to go over after the Easter break and see her for a week or two, I ended up staying till she came home. Once I arrived she was off with me, little interest in sex, not wanting to cuddle or be intimate etc... 

She assured me it was just because of her period cycle.

She came on a couple days later and everything was back to normal once her period was over.

We both enjoyed the time with each other as we hadn't seen each other in person for 4 weeks.

Once placement was over and we came home together, we had 11 days until our holiday.

During this time I was looking for another job and got a job offer which I have now accepted.

During our holiday she kept mentioning France, which every time she mentioned France it put a downer on the rest of the holiday. 

Each time this happened I got more and more annoyed by it.

Now I think I'm annoyed as I'm jealous as I don't get these types of opportunities ever. 

And she hasn't considered me in any of these decisions. 

Now she leaves on Thursday and I've got overwhelming anxiety and nausea that won't go away and I feel helpless. I feel so low and depressed, empty inside and I've already anticipated the low moods and loneliness as I do not do well by myself. She just sees this as me having trust issues but just to clarify I do trust her despite the damage of trust.

I have tried to setup a plan with her, ie when to talk every day and to let me know if she is going to be busy rather than ignore me. But she just lost it and said that I need to have more trust in her.

I feel horrible for the way I feel about this but all I've wanted to do the last few days is just sleep and not leave my bed even though I'm on anti depressants and this is not normal for me.

My mind's gone to places I never thought it would out of jealousy. It's made me want to sign up for a volunteering trip abroad for two weeks once she's back so she gets to feel how it feels to be lonely. I don't want to treat her like that but even she has agreed with me that she would be pissed off if it was on the other foot.

Please tell me if I'm out of order for how I feel?