Oh cool, Jestem Polska dziewczyna!
Jak się masz?
And yeah, like the folks in here have been saying. The fears you're having aren't irrational. Your insecurities aren't irrational.
First and foremost, never EVER feel guilty for having a feeling. No matter what you're feeling, its ok to FEEL it. Its the actions afterward that are important to have a grip on.
What's helped me a lot with insecurity and jealousy issues is to try this; as soon as i feel that icky queezy sensation in my gut, like jealousy or fear, I stop, take a breath, and say to myself "right now, I am feeling jealous." or fill it in with whatever it is I think I'm experiencing. I say it to myself and then say "its ok that I'm feeling jealous. This is a perfectly normal reaction for me to be having."
And that's true for you too, and anyone. Whether you're feeling afraid, insecure, angry, happy, sad, ecstatic, nervous. First you tell yourself that you're allowed to feel that way
THEN try and understand WHY you're feeling that way. "I'm feeling jealous right now because my partner is going on and on about the stripper his buddies at work hired for his birthday", that sort of thing can be broken down "I'm upset because I was not involved in the enjoyment that brought him", "I'm upset because he may have enjoyed her body more than he does mine" and on and on... and from there I can say "I can't possibly expect to be the ONLY thing that makes him happy, so why should I be upset when he has pleasurable experiences without me? Its ok." and then, "so what if her body is better than mine? Will he pick to spend his time with women with better bodies than me, just because they're better looking? No, so what does it matter if she looks better than me?"
(there are more avenues in this particular scenario, and in the end I can practice this sort of behavior until that gripping, icky feeling in my gut stops happening when he mentions other hot women. Or I can decide that it takes too much energy for me to spend time having this break-down in my head, and ask him to please stop talking that way in front of me for my sanity)
It took me a while to get good at breaking down why I'm feeling a certain way, but the point is that it will reveal what's REALLY bothering me, and then I can work on the real issues, instead of reacting to the pure feelings I'm having.
So next time you feel spiteful, or feel as though you're going to say something mean or hurtful to punish her for making you feel insecure, STOP. Take a breath and say to yourself "I'm feeling spiteful, and I'm I want her to know how much what she just said upsets me". Then what you can do instead of making a sharp tongued remark, you can tell her "what you just said made me feel really insecure right just then. Can we talk about that?" And then work it out when you're more calm. It doesn't have to be right then. At that very moment you can even add "I'm feeling insecure, please tell me something you love about me for a second."
And she should be able to help you with that. Those are really important requests to be able to make, and to feel entitled to, which you are. You are free to ask for anything you want. Yes, your partner can always say 'no' to a request, but at the very least you're making your feelings known instead of squatting on them and letting them fester.
This is just some practical stuff i wanted to write out because its helped me a lot. It takes everyone in this world a good deal of control over their emotions to do this, not to mention patience and energy to be that honest with yourself, and THEN be that open about it to your loved ones. But its been an invaluable tool in my arsenal against the insecurities in my everyday life. I hope this helps!