Getting to more specifics -- I saw in your other post that you have a son. Is that your partner's son as well?
changing the locks? ... Is the house in your name only, both your names...? Rental or owned?
If you decide to end the relationship, there'll likely be a few different areas to work on: doing what's best for your son, having safety and legal stuff covered, and then working on your own emotional process.
These are good aspects to consider. As my observation, I would include this as well ... what you can do now even
before voicing your intentions or taking action is to (1)
privately and confidentially consult some attorneys, lawyers or solicitors so you can grasp the various issues, complicated legal pitfalls of unwinding your relationship and possible strategies for success
before mentioning the topic to your partner and (2) interview some counselors and choose one who seems most helpful for your needs and circumstances.
Once you know where you stand, then in the future you can arrange for your minor child to also benefit from objective counseling. If this is also your partner's child then this may be a matter for a court or mediator to step in if your partner opposes. (My lawyer told me, Courts love counseling!)
Lawyers can advise you which steps you can take and when, as well as which actions need legal processes in place first. For example, you may not be legally entitled to simply lock out your partner if this is partner's current residence. Follow the rules... and some rules may have legal basis yet not appear to make common sense to you or me.
Same goes about legal advice with respect to how to handle child exchanges and parenting schedule, of course if your partner is also the legal parent.
You don't have to hire the first lawyer you interview. Lawyers often offer inexpensive consultations to hear an outline of your circumstances and then offer possible strategies and legal support as needed.