How do I approach vacay with my MIL who seems to have an issue with me?

Hi everyone, for context I (26F) have been with my boyfriend (28m) for 6 years. I have always had a tight relationship with his family as my parents moved back to Italy a few years ago.

Don’t get me wrong, I have had a good relationship with my MIL throughout the years, often sharing opinions on fashion, life and celebrities etc although I have always felt like she has her limits to the amount of emotional support she provides me. It’s been really hard not having my own family and she knows that but whenever I talk about that kind of stuff, she shuts it down(not that I should expect this from people, but she had gave support to his brother’s girlfriends).

Our relationship has changed over the last few years, she often makes comments towards me that no one else seems to notice. I have wondered if this is just me being sensitive and have tried to block it out but this feeling just keeps coming back up.

For example, she often makes comments about wanting my boyfriend all to herself. She plays this off as a joke but says it so often that it kind of diminishes the ‘joke’ aspect.

She’ll often do things that make me feel really disrespected too.

For example, when me and my boyfriend moved into our current apartment together, she made plans with him on moving day. For extra context, I let him come to the apartment later on in the day as I accidentally made him wait at the apartment for a couch delivery and entire week early. She took him for lunch and this then carried on throughout the day. I was upset with my boyfriend for this but wanted to overcome the situation quickly so I wouldn’t remember that day as being negative.

I have allowed her to be part of our journey in buying our own place but at times, felt like she was kind of overstepping boundaries and wanting to be part of the process that should be between me and my boyfriend.

I am super excited about the new place and will tell her the things I’m excited about for it when I see her. Her response to this is poor, she never really says anything back or adds to my thoughts. It feels like I’m talking to a brick wall.

The final thing I wanted to mention was that whenever me and my boyfriend have disagreements in front of her (nothing big just very normal disagreement in a relationship) she gets involved, sides with him and tries to make it into a bigger thing than it actually is, every single time.

These are just a few examples, I could go on forever.

But yes, I am going on vacation with my boyfriend and her in a few weeks. We’re going to Portugal and I’m leaving them half way through to go to see my family in Italy (this worked well for me as I didn’t want to spend a huge amount of time around her).

My issue is that I really don’t know how to approach this situation in a way that still allows me to enjoy the vacation. How do I go into this without letting her attitude towards me ruin the whole trip? I am a very emotional person and I worry that if she is really rude towards me throughout the trip, I might explode and ruin the trip myself.